Ocean Lakes is our favorite. It is clean, you can get a site on or near the ocean and most sites have concrete pads. Indoor pool and many other amenities.
Myrtle Beach Travel Park on the north end is also nice. I don't believe they have added concrete pads but it is otherwise a nice, ocean front RV park.
We've never stayed at Willow Tree but it has a stellar reputation. It is just that we go to MB to be near the ocean and Willow Tree is miles away.
If you like live shows, both the One show at Alabama Theater and the Carolina Opry are really great. They will both be doing their holiday shows during that time.