As said, Spring after the snowbirds leave is the best time. Summer is too hot, and the fall is still in hurricane season. You need reservations way ahead .... State Parks take reservations on line at exactly 0800 11 months before the date you want - you find out what is going to be available ahead of time, get ready, watch an atomic clock, and try clicking at exactly 0800. If you are looking for the winter season, thousands of others are clicking at the exact same time, so it is like a lottery. You can stay in the State Parks for two weeks at a time. If you want to take a chance, and are flexible, you can keep watch for last minute cancellations, but they are few and far between. That being said, the State Parks are the nicest places in the Keys, and the cheapest. Bahia Honda is the closest to Key West, but Curry Hammock is less than 60 miles out of Key West. As far as Key West goes, the main downtown is mostly a party spot. There is plenty of interesting history and historic sites. If you have bikes, taking the camper to the free parking lot at Atlantic and White Streets out near the beach, and riding the bike the mile or two into town is the easiest solution to limited parking. I would recommend take the 'Conch Train" to get the lay of the land and point out all the points of interest, then go back and visit those that interest you. There are a couple of campgrounds on Stock Island a few miles out of Key West - Boyds, Leos, and El Mar - all would be fine in a B. We stay in Geiger Key Marina and RV Park about 10 miles out of town for all February, and you can catch odd and end sites there if you are lucky. Good restaurant on site, and free, but noisy air show from the adjacent Naval Air Station all day long.