Folly Beach has restrooms and a great pizza place near the beach. A couple blocks before the beach is Crab Shack, excellent restaurant.
Isle of Palms Beach was also a fun fly. Mt Pleasant has a Longhorn Steakhouse - bacon wrapped fillet mignon with shrimp was way over the top excellent.
I flew at both beaches twice. Free parking available on the side streets off the roads running parallel to both beaches, pay parking on the parallel roads.