Come in the RV or stay in a waterfront cottage. Life is good at just about all of the Florida Keys camping locations, and here you get mega activities. Boating is really nice as you can buzz between the crystal clear waters of the Gulf of Mexico and Atlantic Ocean. Staying on an island with water in every direction means a party by the campfire night of the week. We Had a Blast and enjoyed the SUP and dockside fishing.
There are some nice camping spots in the Keys, and prices are cheaper away from Key West. We used to do the KOA, but like staying here a lot better. Most of the year it is wide open, as warm months mean lots of vacancy. Bring the RV to really have fun, or go with the Cottages. Fiesta Keys is a true beachfront resort, just know about your distance to the other big city islands.
You'll find amenities and activities designed to please everyone in the family, we tend to do mostly watersports. Go on one of the eco tours to see lots of critters in the backcountry. I prefer to stay in the larger islands, but the summer pricing here is just too cheap.