Wife and I are both 29 and it seems that every campground we go its filled with older people (no offense to anybody)
First of all that is your loss as you will miss out on learning more about RV'ing, etc. by not interacting with seasoned campers. :C
1. Look for CG's that are close to attractions, big amusement parks, etc.
Those CG's are loaded with campers with kids!
2. AND don't forget to stop at any and all
Yogi Bear's Jellystone Park CG's
= kid havens!
http://www.campjellystone.com/find-a-park/ All us 'old folks' as you call us, over the age of 30, don't go near those so you will be safe. :W