I think the biggest variable is the kid(s). If you have a kid who wants to do it, and can stand several days on the bike, then no problem.
I took my daughter on her first overnight bike tour when she was 9; we rode old three-speed bikes about 40 miles each day, camping out one night on a sod farm near a friend's house. She was 9.
After that I very luckily picked up a used Counterpoint Opus II, and we've put about 1800 miles on it --more than half of that being three or four short tours with my daughter. The longest was 6 days of riding, camping out two nights.
Here's a few pictures from a three day tour we did at the beginning of June, around southern NJ:
This tandem weighs more than two solo bikes put together, but it's very comfortable (especially for the stoker). So far I haven't been able to fit her on a solo bike I consider good enough for touring. She's a little kid and I want her on a bike small enough that she can handle it well. Maybe by next summer....
She wants to ride across the country. So do I, but I'm not sure I can get away with a summer vacation that long.