On the way down:
Lake Cumberland RV Park - Area Attractions
An hour off the freeway. Has a natural woodsy Kentucky feel.
Museum Home
Huge selection of aircraft and walk through museum. Georgia.
On the middle west side (Tampa bay area):
Dunedin to the north has a cool small town feel. Not sure what else is there besides electric go kart racing.
Downtown Sarasota itself is packed with fast snowbird traffic, but tons to do there. Ringling museum. Mote Marine Laboratory & Aquarium. Selby Gardens plants. Music hall. Lido Key/St. Armands has a nice shopping/restaurant/walking area. Siesta key is a top rated beach.
South of that:
Venice is a quiet, very relaxed area w/good beach. Fishing from the pier/jetties.
Sanibel/Estero has a quirky little small town area feel and is fun. Only spent a day there but would go back.
Keep in mind from Michigan to the central west side, Florida is half of the drive but traffic is easy once you're in-state. The freeway around Atlanta on I-75 is hilly and packed with dangerous fast moving trucks. The first "Florida Welcome Center" is fake, and in Georgia. Fill up gas in Georgia.