We've come to like Gulf State Park, near Gulf Shores, AL a lot. Sites are reservable for continuous occupancy from November to April, moderate temps, very snowbird friendly, and overall a well run Park. It was rebuilt a few years ago after a hurricane, and it's extremely modern, right down to a wi-fi network for campers.
There are about 500 sites, and they are laid out fairly loosely. The only problem is how far in advance you need to make your reservations to get in for the season.