My friend just got back from her family reunion. They had it at Estes park Colorado YMCA family camp. For 4 days, their family of 6 stayed in a cabin, had activities to do, and the food was made and served to them. It cost them $1000.
She told me it was a great time, and they also had a big gathering room for games and hanging out. The activities were age appropriate and included in that price.
If anyone is interested in looking at it a bit, here is a link. I have not played around on this site, yet, but I see that there are many many states with options in them. Oh, they also only had to reserve it 2 months ahead of time. Anyway, it's worth looking into for future family reunions!!