Jellystone RV park in Eureka, MO is about 15 minutes West of I-270. Looks like more of a campground experience than RV park by looking at the website. A bit pricey in IMHO. We drove through Babler SP, it is nice. We drove past Sundermeier RV park in St. Charles. Convenient but basically a parking lot. St. Charles is also a nice place to visit. There is also the Red Barn Rendezvous in Edwardsville, IL it is a small Rv park on the frontage road by I-55 & IL Rt 143. The Zoo, Science Center and Grants Farm are all free. Have a great visit!
Marcia