Kind of depends on what you want. For the RV Park type setting
Holiday Travel Park of Chattanooga, is good.
Chester Frost Park and
Harrison Bay State Park are across the Chickamuga lake from each other. Chester Frost has more lake front sites but sites are close and open. Harrison Bay will have a more woodsy feel. Last there is
Cloudland Canyon State Park about an hour south of Chattanooga on Lookout Mountain.