Prices on a per-square-foot basis rose in 78 of the nation's 100 most-active housing markets, another signal that a recovery is afoot, according to the latest figures from the field.

For the most part, price-per-square-foot increases were in single digits. But several "core-based statistical areas," including formerly downtrodden places like Phoenix and Fort Myers, Fla., notched strong double-digit gains, according to data from Pro Teck Valuation Services of Waltham, Mass. (Uncle Sam defines a core-based statistical area, or CBSA, as a geographic "micropolitan" area of at least 10,000 people who are tied to the urban center by commuting.)

Price per square foot is the great equalizer when it comes to studying housing prices, because it adjusts for product mix. Median house prices are interesting, says Michael Sklarz of Collateral Analytics, which supplies Pro Teck's data. "But if you want to know how much houses are selling for, you need to know their price per square foot," he says.

That's why this column is switching horses, from quarterly reports on median prices supplied by the Federal Housing Finance Agency to Pro Teck's numbers. FHFA's data have been the basis for the Housing Scene's price columns since it began more than 30 years ago, long before Case-Shiller and other rip-and-reap reports became popular.

But the government's numbers are highly susceptible to the vagaries of the market. The FHFA has reported surges of 40 percent or more in median house prices for some metropolitan areas during reporting periods when many more higher-cost homes than usual changed hands. Likewise, sales of an unusually large number of lower-priced dwellings can distort the average on the downside.

Granted, Pro Teck's data also can show huge changes. But price per square foot "normalizes" for swings in product type and size, which presents a truer picture of the market.

Pro Teck's figures have another advantage in that they are more current than anything else available. Numbers from other indexes can be three to six months old. But Pro Teck says it catches sales data almost immediately from 850 multiple listing services nationwide. Once a deal closes, it is captured in Pro Teck's database, which is updated at least daily and culled 15 days after the end of each month.

Like the FHFA's figures -- the ones from its Mortgage Interest Rate survey of the nation's largest metro areas, not its monthly House Price Index, which is another lagging indicator -- Pro Teck's figures cover jumbo loans over the conforming loan limit. To do otherwise, as the oft-quoted House Price Index does, would be to underreport a big swath of sales, especially on the coasts.

Pro Teck's numbers also are more detailed than any others, drilling deep into ZIP codes and neighborhoods. National numbers make for great headlines, but they are absolutely worthless for buyers and sellers who need to know what's going on in their local markets.

Pro Teck's numbers are not without their drawbacks. For example, new-home sales, which tend to lead the market up and follow it down, are not fully captured. But in that savvy builders these days are listing their products on local multiple listing services -- 790 of the 9,292 current listings in the immediate Washington, D.C., area are for brand-new houses -- Pro Teck catches at least some builder sales.

Another shortcoming is that the Massachusetts company sells its data to investors, lenders and loan servicers. Government figures are preferable to those from a private company trying to make a profit from them.

That said, Pro Teck's statistics are as good as they come. Here's what the company's figures for the latest three months as of Aug. 1 tell us:

Phoenix and Fort Myers are rebounding very well, as are San Jose, Calif., and Detroit. The median price per square foot paid in the Phoenix-Mesa-Glendale CBSA rose by a whopping 31.2 percent from the same period a year ago, from $64.03 to $84.01. Interestingly, the median house price in the Phoenix CBSA was up 31.4 percent over the same period, from $118,000 to $155,000. In the Fort Myers-Cape Coral CBSA, the median square foot cost was up 19.4 percent, from $59.46 to $71.

In the San Jose-Sunnyvale-Santa Clara CBSA, the median square foot cost rose almost 19 percent, from $377.86 to $449.51. Nearly $450 a square foot is a lot to pay for a house, which is why the median house price in San Jose was $765,375 as of Aug. 1. But it's even more expensive in the neighboring CBSA of San Francisco-San Mateo-Redwood City, where the median price per square foot is $476.95, up 5.9 percent from a year earlier.

The Detroit area also is showing signs of a strong recovery. The average cost per square foot in the Detroit-Livonia-Dearborn CBSA rose 16.4 percent, from $41.54 to $48.34, while the price in Warren-Troy-Farmington Hills increased 10.3 percent, from $68.01 to $75.

Overall, square-foot prices were up by double digits in eight CBSAs. On the flip side, none of the 22 core areas that registered lower prices per square foot over the last three months saw more than an 8 percent decline. The largest slides were in Gary, Ind., down 7.8 percent, and Birmingham, Ala., at minus 6.4 percent.

For what it's worth -- and it isn't worth much -- the median price per square foot for the 100 most active markets combined was $89.75 as of Aug. 1, a 2.6 percent increase from $87.44 at the same time a year ago.

Most people refinance to save money. That usually means jumping to a lower rate. But you also can save big bucks by trimming the term of your loan, possibly at the very same low rate.

Most lenders today offer the same 30-year rate on mortgages with terms of 20 to 29 years, according to Karen Mayfield of Bank of the West. And most offer the same 15-year rate on loans with durations of eight to 15 years.

You may not save any money immediately, at least not in terms of your monthly payment. But you could save a bundle in interest over the shorter life of your new mortgage. Plus, you'll build a nest egg that much faster.

The potential drawback to shorter-term mortgages is that your tax deduction for mortgage interest won't be as large. But that's a questionable disadvantage.

For one thing, interest is cash out of your pocket. Why spend the money if you don't need to?

For another, mortgage interest is not a dollar-for-dollar write-off. Rather, the deduction is based on your income-tax bracket. So if you are in the 15 percent bracket, you'll get back only 15 cents for every dollar in mortgage interest you spend.

Then there's the question of whether mortgage interest will remain deductible. Granted, it's a long shot right now that Congress would eliminate the benefit. But make no mistake, the once-sacrosanct write-off will be on the table if and when lawmakers ever reform the nation's tax code.

So, with the deduction argument out of the way, let's look at some possibilities using, for simplicity's sake, a loan amount of $300,000.

Say you have a 4-year-old, 30-year mortgage at 6.5 percent, with a monthly payment to principal and interest of $1,896. If you refinance at 4 percent into a new 30-year mortgage of $288,000 (your present balance of $285,179, plus $2,821 in closing costs wrapped into the loan amount), your payment will drop to $1,375, a significant monthly savings of $521.

But you'd be starting all over again. As a result, on top of the $76,196 in interest you've already spent on the original mortgage, you'd be paying an additional $206,984 in interest over the term of the new loan.

Sure, most people don't keep the same house, let alone the same mortgage, for 30 years. Indeed, the average life of a home loan is about seven years. But if you do, if this is your final castle, you will be paying for it for 34 years, not 30.

Now, suppose that instead of opting for a lower payment, you decide to shoot for the same monthly payment but reduce the term of the loan. A new $288,000 mortgage at 4 percent over 20 years will run $1,745 a month.

That cuts your monthly outlay by about $150 and saves a whale of a lot of interest -- $130,854 for the 20-year loan at 4 percent vs. $206,984 for the 30-year loan at 4 percent and $382,633 for your original loan.

Better yet, you are not starting over. Again, most people don't keep their loans forever. But as Mayfield rightly points out, people's lifestyles do change. And as they do, it's sometimes necessary to have a nest egg.

Say, for example, that 10 years from now, Junior wants to go off to college, or Priscilla wants to get married. Either way, you're going to need some cash. Good for you if you've been saving regularly for these kinds of events. But if you haven't, you still might be able to borrow what you need at the going interest rate.

Another option is to take it out of the equity you've built up in your house. Just how much equity might be available a decade from now will depend on two factors: appreciation, or how much your place has increased in value, and the term of your mortgage. Only one, the loan's term, is a sure thing.

If you opt for the new 30-year loan in the above example, you will have accumulated $51,102 in equity by making your payment every month over 10 years. Why so little? Because in the early years of any mortgage, the lion's share of the payment goes to interest. In fact, it isn't until the 20th year or so that more of the payment is earmarked for principal than interest.

Mortgages with shorter terms amortize, or pay down, faster than those with longer terms. So if you opt for the 20-year loan above, you will have amassed $115,624 in equity after 10 years. That's more than double the equity buildup.

Shortening the length of your mortgage isn't for everyone. But if you are comfortable making roughly the same payment as you are now, it is worth considering. "Do the math," Mayfield advises.

Another sometimes overlooked refinancing option, especially if you have a good idea how long you might keep the house, is a hybrid adjustable mortgage, one with a rate that is fixed for five or seven years before it begins to adjust annually.

Most people are jumping out of ARMs to fixed-rate loans these days because of the certainty the new loans offer. "Knowing your monthly payments won't rise in the future provides a lot of peace of mind," Mayfield says.

But hybrid ARMs offer a degree of certainty, too. And adjustable loans aren't nearly as dangerous as many people think.

With today's fixed rates at near record-low levels, the rate on ARMs surely will rise when the fixed-rate period expires five to seven years from now. But caps on the annual increase will limit the pain if you misjudge your expected moving date.

PLAYA FLAMINGO, Costa Rica -- When it comes to vacation homes, there's something for everyone.

You can own the whole thing or just a piece of it. Vacation homes are everywhere -- in the mountains, in the city and from sea to shining sea, including here at The Palms on Costa Rica's Pacific coast. And there is evidence that after a six-year lull, sales of vacation homes are finally starting to gather steam.

While the primary home sector remained in the doldrums last year, sales of vacation homes rose 7 percent, according to the National Association of Realtors' latest tally. Other forms of vacation ownership also are showing improvement. Sales of "fractionals," an upscale category of shared ownership that includes multiweek intervals, private residence clubs and destination clubs, increased 4 percent in 2011, according to the annual count by Ragatz Associates.

Time-share sales were up 2.4 percent in 2011 and 14.1 percent, year over year, in the first quarter of 2012, according to the American Resort Development Association.

While the uptick in 2011 was "nominal," says Richard Ragatz, who heads the Eugene, Ore., consulting and research firm that bears his name, "a significant number of developers said that sales were better during the second half of 2011, giving the impression that the bleeding has finally stopped and we may be turning the corner."

If you haven't been in the vacation property market for a while, here's what you'll find:

-- Whole ownership: According to the Census Bureau, there are now about 8 million vacation homes -- recreational property purchased for personal use -- located in practically every burg and hamlet nationwide, and in some major cities, too. (The total does not include the uncounted millions of vacation homes available worldwide.)

The choices are myriad. You can buy a small cabin in the woods, a retreat on the slopes, a beach bungalow or a condo in Gotham. The prices also range considerably, as do the headaches.

No one uses your place but you and your guests, which is usually a positive. But you pay for all the upkeep. And you pay for all the downtime when the house or apartment isn't being used.

-- Time shares: More than 8 million people own a week or two at their favorite resorts. What's more, 42 percent of last year's time-share buyers were repeat buyers who were either adding to their weeks or moving up, perhaps to larger units or to more lavish properties. That's a sign that despite the negative press, at least some people enjoy time sharing.

According to the American Resort Development Association, there are more than 1,500 time-share resorts with a total of nearly 195,000 units. As with location, time-share prices are all over the map. But sharing the same unit with 51 other owners is usually the least expensive way to own a vacation home. The average price per week was just over $15,000 in 2011.

Better yet, most resorts belong to exchange banks, where you can deposit your week at your home resort and take out time in a comparable spot elsewhere. So, as much as you may love your place, you are not stuck in that one spot every year. The amount of time purchased often is now expressed in "points" as opposed to weeks, allowing even greater flexibility.

On the other hand, time shares are a lousy investment. That's why they are sold as a hedge against inflation, or "vacation insurance." And they are difficult to resell, even at less than what you paid.

There is some evidence that developers are starting to embrace resales, which have been a black eye on the business. According to a survey by industry publication Perspective, two-thirds of respondents said developers need to create in-house resale programs, and 72 percent said resale information should be included in the original sales presentation.

-- Fractionals: These are upscale versions of time-share resorts, where you buy larger interests, typically in four-, eight- or 12-week chunks. Prices are also higher -- the average last year was $131,000, according to Ragatz -- and so are the monthly carrying costs, which can be hefty. But you get more usage and better exchange possibilities.

-- Private residence clubs: These are more luxurious yet -– and more exclusive. The clubs offer fully deeded fractional ownership with all the services and benefits of a five-star hotel. As with other forms of shared ownership, you pay for only the time you actually need, typically three to six weeks. The average price: $254,000 per share, with annual fees averaging $6,650. There may be no more than 300 private residence clubs worldwide.

Here at The Palms on what is called Costa Rica's best beach, the 33 two- and three-bedroom oceanfront town houses are being marketed as a mixture of both full ownership and fractional ownership of one-eighth or one-tenth interests. A combination of whole ownership/private residence club is something many of the major properties are offering these days, sales manager Mark Randall says.

Whether you buy the entire unit here for $1.1 million or an eighth of one for $129,000, you get all the services, including the ability to trade places with owners in other properties. Obviously, full owners can visit anytime they like. But part-timers can usually grab five to six weeks or more, depending on availability and how flexible they can be.

"There's no arbitrary limit on use, and owners are not penalized for how long they stay," says Randall.

-- Destination clubs: Fewer in number -- only six responded to the annual Ragatz survey -- destination clubs give members access to a collection of vacation homes worldwide. The average membership fee: $273,000.

Consistent with other types of interval ownership, clubs offer different levels of reservation priority, personalized services and amenities, such as spas and private chefs.

Similar to membership choices available at country clubs, buyers can choose between equity or nonequity clubs. But either way, you get to enjoy all the benefits.