Hilton Head is an interesting market. There are a lot of 3 and 4 bedroom villas available for relatively inexpensive nightly rental (depending on how in-season you are looking to go). THis is because there are a lot of golf foursomes going to play the courses, and the golfers want their own bed and their own bedroom. There are also plenty of homes for rent, many with pools. There are a lot of options that can be rented for less than the MF on a timeshare. There are good options for golfers, tennis players, cyclists, hikers, kayakers, and beach goers.
There are also timeshares in the Myrtle Beach/Wilmington area. These areas are overbuilt, so again, you can get great deals without being an owner.
Charleston and Wild Dunes is a great area, but I am less familiar with the market there.