The closest beaches distance-wise are probably the barrier islands around Charleston. Edisto Beach, Hunting Island, Isle of Palms, Kiawah, Folly Beach are all 6-6.5 hours.
Wilmington is 7.5.
Some useful pages for you to check out would be
transportation and
weather in Tennessee. Here you will find information on how to get from A to B and also what the weather will be like when you arrive. Also you should look at the
things to do pages as this will highlight some of the best attractions in and around the area.