Kerry,

I don't know if it's your thing, but the Congressional Medal of Honor Museum is located on the USS Yorktown, a WWII carrier located at Patriot's Point.

http://www.patriotspoint.org/exhibits/medal_honor/

Fort Moltrie is interesting.
I viited Magnolia Plantation. Quite nice in May. Touring the grounds you can see why the Charleston area is referred to as "low country"
http://www.magnoliaplantation.com/index.html

The Battery is quite nice.
http://www.celebratecharleston.com/

Enjoy your trip.