I bought a class A private sale that was originally a rental. Is it perfect? No way but the price reflected its condition. My best advise to you is analyze your mechanical ability. My wife and I are also in our 30's with a 4 and 2 yr old. We couldn't afford to do this if I had to pay to have the maintenance and repairs done. So far nothing came up I couldn't fix. I also second the bunk model. I have an 07 Coachmen Mirada 350DS and the kids having their own area is golden. They almost always go to bed before us which would make the living area unusable if we had to use it for a sleeping area.
I never owned a camper of any kind before but I can't imagine doing it in any other than a class A. My kids love it!
What state are you from? I would love to go camping with others that have kids the same age as mine. I live in Gilbertsville PA which is about 30 mins West of Philly. PM me if you don't want to say publicly.