Jellystone Park, Eureka, Mo
I spent 6 days visiting the St Louis area with my daughter, son-in-law, and two grand-daughters. We decided to stay at the Eureka Jellystone Park. What a great decision. They have a super staff. They allowed me to pick a different site than the one they scheduled me for and went beyond the usual to make sure I got on the site and hooked up. They have a lot of good activities for children young and old. Camp fire rings at each site allowed for s'mores each night. My older GD got some pirate training one night at the veranda. She is still talking about it. The train rides were great and the younger GD loved the meetings with Yogi Bear. The staff at this park are all excellent with the young kids and I do believe they enjoy the activities as well as the kids do.
If you are in the St Louis area with young children you could not pick a better campground than the Jellystone Park. They have sites for all types of camping from tents to MH. Give them a try