Jeremy,
I've camped (RV'd) at a number of places "on the beach". I clarify because there are a lot of places (mostly state parks) along the pan handle that have beach front access, but the actual camping sites are back and do not have any actual ocean view.
True "beach" camping that I have done:
Myrtle Beach (Pirateland/Lakewood/Ocean Lakes)- VERY large campgrounds. I've stayed at all 3. (They are next to each other south of MB) You can get pretty close to the beach, but they have a berm that blocks some of the view. Personally, too big and crowded for my liking.
St. Augustine, Fl (Beverly Beach)- Beverly Beach Camptown RV Resort- Smaller campground wedged between A1A and the ocean. Only 2 rows of sites. One backs up to a sea wall with a drop to the beach, but the views are really nice.
Destin- Camping on the Gulf- This was my first actual camping ON the beach. I've camped here 4 different times. Smaller campground, but INCREDIBLY tight sites (especially the beach and beach front sites). It is also VERY expensive. If the price of a Fort Premium site at Christmas scares you, don't look at this place. If I wanted true beach front camping though, I'd consider staying here again.
In case you're interested in how close you can get there.
There are places in the Keys that are waterfront I have drove past, but I haven't stayed at them.
As others mentioned, Gulf State Park is nice, but the camping sites are not right at the beach. The park does have over 2 miles of beach front though. Very nice.
Topsail and Henderson SPs are in the Destin area, but neither have actual beach front sites. They are also hard to get reservations.
j