We have stayed several times at Sun-n-Fun with our daughter. It is located in Sarasota FL. Not sure if this would fit the location where you would like to be. Prices were descent and kids were welcome. We have been down a couple times over Christmas. My daughter was 8 and 10 when we stayed.
Beaches were nice. You can go on a day trip to Sanibel Island, state park is close by, Tampa to Bush Gardens, and depending on which way you are traveling you could stop by at Weeki Wachee to see the mermaid show. She might be a little old for that but...
They are also big rig friendly.
We may be back down there this Christmas I can swing the time off at work.