What would you recommend as far as must see places and best places to eat?

If you're staying in Folly and want unique but casual I would go get some oysters and beers at Bowen's Island Restaurant between Folly and the mainland (James Island). If you want memorable SNOBS or any other of a hundred restaurants are good downtown. In May you might find one of the rooftop bars with a view of the harbor. As far as must sees, there are all the historical attractions, Fort Sumter National Monument, Fort Moultrie, Fort Johnson. Friends of the Hunley is pretty cool. You can walk to plenty of attractions such as the Old Exchange and Provost Dungeon and Historic Charleston City Market. Grab brunch at Fleet Landing. Then there are plantation tours up about any river. Charleston Tea Plantation at Wadmalaw. Shem Creek is fun. Plenty of options.