Ever hear of Long's Retreat (over near Chillicothe)?
Famil owned, well ran and maintained, in the very scenic hills of soithern Ohio.
You can camp or rent one of their cabins, which come in various sizes/features depending on what you want. There is alot of stuff for the family to do.... swimming (nice lake w/well maintained beach, excellent water slides, paddle boats, canoing, go-cart track, putt-putt golf, driving range. There is also an arcade and other rides for kids.
We've been down there twice and really enjoyed ourselves immensely.
It's really inexpensive, and if one wants, they can get a family pass (comes with a wrist band) where the water slides, putt-golf are free.
Rocky Fork and Lake Hope are also near by.
Here is their website....