Would you consider only visiting one area?

You could easily spend all your time in the Savannah/Charleston area -Hilton Head is in the area, as is Beaufort. All offer unique options, and you may not want to be so tied to such a short timeline.

OR

Come up to NC from ATL; visit Asheville and some of the (many) small towns in the greater area - and perhaps head over the Great Smokey Mountain National Park; or drive along a portion of the Blue Ridge Parkway. This would be a particularly gorgeous trip if you travel in Oct, as you would hit leaf peep. Depending on the final lay-out of your trip, you might do better to fly in/out of CLT.

Great food can be found in both areas!