Over the next 10 years, the number of U.S. households led by someone 65 or older will increase by nearly 11 million. And a surprising number of those older people could soon move to larger, rather than smaller, homes.

"Stunningly, three out of 10 older households who've already moved actually upsized. And many more are renovating the place where they now live," says Ken Dychtwald, a psychologist and author who heads Age Wave, a consulting firm that tracks aging trends (www.agewave.com).

Age Wave partnered with Merrill Lynch to produce a new study of baby boomer housing and lifestyle preferences that included a nationally representative survey of more than 3,600 older Americans of retirement age.

According to the survey, retirees' top reasons for upsizing were to have a home large enough for family members to visit (33 percent) or to live with them (20 percent). One out of six retirees has a "boomerang" child who's moved back in with them.

Although a surprising number of retirees are upsizing, the Merrill Lynch study reveals that a solid segment of older Americans still plan to downsize. Those in this category cite multiple factors including greater freedom from financial burdens (64 percent) and fewer upkeep demands (44 percent).

Are you a boomer perplexed by the array of housing choices available to you? If so, these tips could prove helpful:

-- Factor in both your preferences and those of your partner.

If you're expecting to retire and live on your Social Security plus limited withdrawals from a small retirement fund, you may have no choice but to step down to a smaller, less-costly-to-maintain property. But if you've accumulated more substantial retirement assets, you and your spouse could have many more interesting housing options and may need to reconcile differences of opinion.

Rosemary McMonigal, a residential architect who's advised clients for 31 years, recommends that couples with differing visions create priority lists and acknowledge the validity of each other's housing preferences.

McMonigal says many of her retirement-age clients favor downsizing over upsizing. Still, she says it's not unusual for one member of a pair to prefer a larger habitat to gain more personal space.

If you and your spouse disagree on how large a home to buy for your retirement needs, McMonigal suggests you let go of preconceptions and find a way to compromise.

"Discussion works," she says.

-- Try to avoid buying a retirement property with superfluous rooms.

McMonigal is a proponent of the "not so big home" philosophy espoused by widely quoted architect and author Sarah Susanka. As such, she argues that most retirees are happier living in a space no larger than they can actually use rather than trying to pursue a fantasy ideal.

For instance, she says buyers should question the commonly held notion that a home should have multiple dining areas, including a formal dining room, an in-kitchen eating area and an informal dining nook off the kitchen.

McMonigal also suggests you question the common assumption that you should have a dedicated media room and a huge master suite complete with a spacious master bathroom and an adjoining sitting room.

"Most people don't have the time or inclination to use a sitting room for conversation or reading. For that reason, one large armchair in the master bedroom is enough. And media rooms usually go unused, as do extra bathrooms," she says.

-- Realize that the floor plan you select is as important as the size of your home.

Would you like to downsize, but have agreed with your spouse to buy a bigger place?

If so, Ashley Richardson, a long-time real estate agent affiliated with the Council of Residential Specialists (www.crs.com), recommends you look for a home that seems intimate despite its large size.

"It's easy to feel lonely when rattling in large spaces you rarely use, especially if all your grown children live far away," Richardson says.

To locate a large home where you'll feel comfortable, she recommends you avoid a property with a two-story atrium or ceilings that soar 10 feet or higher. Also, avoid a property with an oversized formal living room that you'll rarely use. Instead, look for a place with a relatively large family room where you can both dine and entertain.

"Lots of people like having their family room right off the kitchen, which is the area where people spend most of their time," Richardson says.

-- Remember that the home you buy for retirement may not be your last purchase.

Many people assume that when they buy a home for retirement, they'll live there for the rest of their lives. But it's very common for homebuyers in their 60s to go on to later live in two or three other places during their retirement years.

If you have sufficient financial assets to consider a wide array of alternatives in terms of housing size and location, Dychtwald suggests you investigate a short list of options before committing to a move.

"Remember those college tours you took your kids on? You could do the same to check out different locations and types of housing for your retirement years," he says.

(To contact Ellen James Martin, email her at ellenjamesmartin@gmail.com.)

With spring up ahead, many people living in cramped apartments are yearning for a house with a yard.

"For many renters at this time of year, home ownership sounds like nirvana," says Tom Early, a consumer advocate who was twice president of the National Association of Exclusive Buyer Agents (www.naeba.org).

For many wannabe buyers, the catch, of course, is financial. How can first-timers get an excellent price on a solid property? Steve Israel, the president of a real estate firm that caters to homebuyers, says one strategy is to consider properties were once rental units but are now up for sale.

He says some of the most willing-to-negotiate sellers include those who had to move due to a job change. These are people who moved before their property had sold and decided to rent their place out on a temporary basis.

"They never intended to become landlords and dislike the headaches," Israel says.

The owners of a rental property who live far away are often so eager to sell that they'll give you a very good price, says Sid Davis, a broker and author of "A Survival Guide for Buying a Home."

Here are few pointers for buyers pondering the purchase of a rental:

-- Visit the property when the renters are absent.

With a few rare exceptions, those living in a rental home are usually displeased upon learning that their landlord plans to sell and force them to move.

"Some tenants will openly seek to sabotage their landlord's efforts to sell," by leaving messes or exaggerating minor problems, Davis says.

Davis urges buyers trying to evaluate a rental property to schedule their visits at times when the tenants are away.

"That way, you'll avoid the annoyance of having the tenants follow you around in the house. You'll also feel a lot more comfortable scrutinizing the property. For example, you won't be embarrassed to open the closet doors or kitchen cabinets," he says.

-- Realize that a detailed home inspection is a must.

A fair number of rental properties are overseen by professional management firms. Still, they rarely receive the same level of attention as owner-occupied homes. That's why it's important to make any bid conditional on a satisfactory home inspection.

Without a good inspection, Israel says it's hard to know, for instance, if the heating and cooling systems have been serviced regularly or whether plumbing problems were fixed.

Davis says one way to find a qualified home inspector who serves your area is to go to the website of the American Society of Home Inspectors (www.ashi.org). Another is to ask your real estate agent for recommendations.

"Ideally, you'll gather the names of at least 10 candidates and then narrow your list to three who you can interview by phone," he says.

Davis recommends you refuse to hire any inspector who's also in the home improvement business.

"Watch out for any guy who tries to contract with you for home improvement or repair work," Davis says.

-- Obtain cost estimates for potential repairs.

As a real estate investor, Davis once owned seven rental properties, all of which he's since sold. His experience as a landlord taught him that tenants often fail to tell their landlord about problems unless they become serious.

"Suppose the dishwasher has malfunctioned for a year, yet the landlord has never heard about the problem until a home inspector determines that the dishwasher leaks and must be replaced, along with the subflooring beneath," he says.

Davis says the prospective buyer of a rental, or any property, for that matter, should determine in advance how much needed repairs will cost. Before finalizing your bid, he recommends you get estimates for all the work on your inspector's list. Then make sure these costs are factored into the price you negotiate.

-- Distinguish between houses with superficial vs. serious issues.

In those neighborhoods where available homes are still in short supply and buyers continue to outnumber sellers, bargain properties are now tough to find. Even so, Davis says those who keep an open mind about purchasing a rental unit could still get a good house for an under-market price.

"Lots of folks attach a stigma to buying a rental. So if you're the people who can look beyond that stigma ... you could score a very good deal," he says.

The key to finding a genuine bargain in a rental unit is to carefully consider each property on its own upsides and downsides.

"The reality is that some rental properties -- especially those that have been occupied by tenants for five years or longer -- are a terrible deal that would drain your savings and make your life miserable. But a house that's been rented out only briefly could present you with a wonderful buying opportunity," Davis says.

(To contact Ellen James Martin, email her at ellenjamesmartin@gmail.com.)

Many financial planners advise clients over 55 to pay off their home mortgage so they can live debt-free after retirement. But what if you must draw down savings to wipe out your home loan? Then your choices get much tougher, says Thomas J. Casey, a veteran financial adviser.

"After you retire, you won't want all your money in the ground in real estate. That's the downside of pre-paying your mortgage from your limited savings," says Casey.

An alternative to mortgage pre-payment is to refinance your home loan to lengthen the term and thereby reduce your monthly post-retirement housing costs.

"The upside of refinancing is that it gives you predictably low monthly payments, which is a strong positive for retirees on fixed incomes. But the downside is that you'll pay much more interest on a longer-term mortgage and you won't free yourself of that debt for many years," Casey says.

"The fees for refinancing are substantial. Because of that, it's important to be very sure you'll be staying in that house for at least five to seven more years," Casey adds.

Eric Tyson, co-author of "Personal Finance for Seniors for Dummies," urges those over age 55 to carefully think through any potential decision about real estate.

"If you make a major financial mistake during this time in your life, you'll have much less time to recover from your error," Tyson says.

-- Begin with an analysis of your full financial picture.

Before you retire, you need a spending plan that documents your current expenses and helps you closely estimate your income versus living costs for future years," Casey says.

In the first few years of retirement, he says most people spend roughly the same amount as they did during their working years, though their medical expenses usually rise. But by their mid- to late 70s, however, retiree living costs tend to decline, as interest in travel and entertainment start to taper off.

One way to develop a comprehensive spending plan is with the help of a financial adviser. If you go that route, Tyson recommends you choose an adviser who's compensated on a fee-only basis, meaning the planner wouldn't receive commissions by selling you stocks, bonds or insurance products.

You can locate the names of fee-only planners through the National Association of Personal Financial Advisors (www.napfa.org).

Another option is to hire a certified public accountant to guide you through the planning process. One way to find a CPA who specializes in personal finance is through the American Institute of CPAs (www.aicpa.org). This organization maintains a list of CPAs who've earned the "personal financial specialist" (PFS) designation.

-- Reduce your outlays for financial planning by doing prep work yourself.

The first step in developing a financial plan is to track your current spending patterns. You need to know how much it costs you to live, both in terms of mandatory costs (such as out-of-pocket health care expenses) and discretionary outlays (such as restaurant tabs).

Unless you routinely track these numbers (on paper or with a specialized personal finance tool, such as Quicken), assembling these data can be time-consuming. To avoid paying an adviser to assist with this grunt work, Tyson suggests you scrutinize your account statements and do these tabulations yourself before going to see the planner.

An online retirement calculator can be another handy tool. Tyson recommends the free online calculators available through such investment firms as T. Rowe Price (www.troweprice.com), Vanguard (www.vanguard.com), and Fidelity (www.fidelity.com).

Such calculators can help you estimate how much money you'll need to cover your expenses in retirement.

-- Don't overestimate your home's appreciation potential.

It's true that since the post-recession economy started improving, residential values have gradually risen in many areas. But in most neighborhoods, the upside potential for real estate remains limited. Because of that, Tyson says it's unwise to stake your financial future on the notion that you could fund your retirement by selling your house for a big profit and then moving.

"Of course, it's psychologically comforting to pay off your mortgage before retirement. But it's also true that you'll need probably need much or all of your savings to get you through your retirement years," Tyson says.

-- Don't forget your lifestyle preferences when weighing financial decisions.

Through the years, Casey has noticed that his clients vary widely in terms of how they wish to live in retirement. For example, some intend to pursue expensive hobbies and travel abroad in luxury. Others are happy with home cooking and inexpensive camping trips with their grandchildren. Most plan to stop working entirely, but many intend to work part-time for as long as possible.

Why are your retirement lifestyle expectations relevant to your mortgage planning? Because your living expenses, along with your income levels, can be a major factor determining how much you could afford for mortgage payments.

"In your prime retirement years, you don't want to shortchange yourself just for the satisfaction of having a paid-off home," Tyson says.

(To contact Ellen James Martin, email her at ellenjamesmartin@gmail.com.)