For me its about the when. Summer is full of tourists with lots of kids etc. I like to go down mid Sept. Weather is cooler and kids are in school. I have my pick of restaurants. I like seafood so Murrells Inlet is where I go.
We left one year on the Sunday of the Mopar Nats and stayed for 3 days, it was a ghost town. It was busier at night, but the beach wasn't exceptionally crowded and walking the main drag was down right pleasant. Of course, a lot of the shops weren't open for the down season. Still had a blast.