I've been asked about visiting Charleston and had several readers come to town. I thought I'd give a couple of tips.
Perhaps the most important thing when planning a visit is choosing the time of year. It's hard to beat April and May. The weather isn't too hot yet, and we don't get overrun with tourists until school gets out in June. Be aware that The Bridge Run happens in that time frame. Unless you plan to run, skip that weekend as there are tens of thousands of extra visitors.
If you can swing it, stay in one of the downtown Bed and Breakfasts. Pick one near the intersection of Market and Church and you'll be within walking distance of a lot of the things you'll want to see. Pedicabs are an cheap and easy way to get around, especially after dark.
Once you're checked in, take a carriage tour. There are several companies and they're all good. The tour guides have to pass a test and they're all knowledgeable. There are four different routes, chosen at random so you can't pick the route you want. That's for traffic control. Take a couple of rides. They're not that expensive and you'll really get some insight into the history and architecture of the city.
Once you've done that, you'll have a much better idea what you want to see. Explore at least one of the amazing mansions. I love the Calhoun house also known as the Williams Mansion but there are several others with nice tours. Not far out of town are a couple of plantations. Either Boone Hall or Magnolia Plantation are worth the visit.
After that, it's up to you. The walking ghost tours are silly but fun. A boat ride out to Fort Sumter is definitely worth the trip. Not only do you get the history, but a great view of the city one the boat ride.
If you're not going to visit but want to see more of the town, "Rucker's Reno" was a 6-part series chronicling Darius Rucker's (Hootie) Broad Street house renovation. While the show was focused on the house and renovation, there's a lot of Charleston scenery and history in the show as well. For an even quicker look, you can find "Darius Rucker's Hometown Charleston Tour" on youtube.
Everyone asks about restaurants. There are simply too many good ones to try to list them all but here are a few of my favorites.
Slightly North of Broad - aka SNOB
82 Queen
Fig
Magnolias
Poogan's Porch
Lowland
The Ordinary
and for something completely different:
Bintü Atelier
I could go on but there are plenty of guides, youtube videos and the like, to help you refine your visit. Drop me a note, if you've got questions and I'll do my best to answer.