Charleston is one of my favorite places to visit. If you want to stay on the beach, Isle of Palms/Wild Dunes area is very close. If it's just the two of you, get a place downtown and just walk around. There are tons of fantastic restaurants, shops, art galleries, and parks at your disposal. The USS Yorktown is cool to visit, especially if you haven't been on a big warship before. My wife and I have been trying to find a weekend to return...we always love visiting Charleston.