Although unfurnished, the historical Hampton Plantation is a great stop between Charleston and the Georgetown-MB area. The house is one of those "off the beaten path" sights - it is perfect for "old house" lovers. The cost to see the house is a bargain since it is a state park, and there are lots of photo opportunities. Also recommended in the area are: St. James Santee Church (a small, but pretty colonial church very close to Hampton Plantation), Hopsewee Plantation (just outside Georgetown), the fishing village of McClellanville, and the sights in Georgetown. (Prince George Winyah Episcopal Church at the corner of Broad St. and Highmarket St. in Georgetown is another pretty colonial church. It has a great photo opportunity - an oak in the cemetary has actually grown into several headstones)
There are more historical sites in Georgetown. If you judge Georgetown by what you see on Highway 17, you might think it is a dirty steel town. It actually has a lot of historical sites and decent restaurants without many of the tacky tourist traps in Myrtle Beach and Charleston. Go into the historic downtown; it's small, but nice.