We just came back from vacation and one state park we stayed at was the Kickapoo SP on the Indiana/Illinois border. You had electricity with shared water and I think it had a dump site. There were a lot of trees and it was on a lake or river. There were 2 families doing the work kamping. He said that is how they take vacations with their kids. There were several places within 2 hours or more in Indiana and Illinois depending on your interests.
In Pontiac, IL there was a 4H and Gun club campground that was $12 a nite. It was out in the country and quiet. They have barns and stalls for people to bring their animals for 4H events. Because it was during the week and there were no festivals, carnivals, etc. it was easy to pick your own spot and decide how close or far away from your neighbor you want to be. Downtown Pontiac has museums - old Pontiac dealership, History of Route 66, Military museum (upstairs)- all are free, but of course will accept donations. In the alley behind the Route 66 museum that have John Waldrip Land Yacht that was made from a 1966 School bus that you can tour. Everyone was friendly.
There was a nice, former KOA campground in Elkhart, IN. Some spaces were shaded, some not. You had space between sites. It is a good central location to visit smaller cities, South Bend, Goshin, etc. for different museums, antique stores or Amish museums or farms where you can purchase different things. There is also the RV Hall of Fame. If you are going to stay in that area for awhile, go about 1 hour east to Auburn, IN for 9 different museums for cars, military, etc. It is also not far to the Michigan State Line.
Other places we stayed at were crowded or were military - so we could stretch our money on the trip since we are not full timers.