DEAR MISS MANNERS: I was addressing an informal talk to a mixed-gender group of seniors. Later, one of the ladies pulled me aside and gently explained that women of her generation did not care to be addressed as "guys," even in a group (as in, "You guys may be familiar with ...").
That is the only time I have heard any hint that this was a widely held preference. Was this lady overly sensitive, or should I be mindful to avoid the term when referring to a mixed-gender group?
GENTLE READER: Did you miss the entire era when names of occupations were changed ("firemen" to "firefighters," "stewardess" to "flight attendant") to reflect the reality of including both genders?
Apparently a great many people did, because it was later that the slangy term "you guys" began to be used, not only for mixed groups, but for groups that were entirely female.
Members of your audience did not. They may have been personally involved in the struggle to convince people of what nonsense it was to believe that ladies should assume they are automatically included in a strictly masculine term. Presumably ladies never considered the word "Gentlemen" on a door to be an invitation to enter.
Miss Manners thoroughly agrees with your audience that "you guys" is offensive. "Ladies and gentlemen" is the proper way to address any mixed audience.