Even if you’re just going to confine yourself to the peninsula, I can’t imagine spending less than two nights there. You’ll want at least half a day for shopping on King Street and a full day for seeing various attractions and museums. Keep in mind that one of Charleston ’s key sights, Fort Sumter , will take almost half a day to see once you factor in ticketing and boarding time for the ferry out to the fort and back; plan accordingly.
If you have a car, there are several great places to visit off the peninsula—especially the plantations along the Ashley River. None are very far away and navigation in Charleston is a snap. The farthest site from downtown should take no more than 30 minutes, and because the plantations are roughly adjacent, you can visit all of them in a single day if you get an early start.
While a good time is never far away in Charleston , keep in mind that this is the South and Sundays can get pretty slow. While the finely honed tourist infrastructure here means that there will always be something to do, the selection of open shops and restaurants dwindles on Sundays, though most other attractions keep working hours.
But for those of us who love the old city, there’s nothing like a Sunday morning in Charleston—church bells ringing, families on their way to worship, a beguiling slowness in the air, perhaps spiced with the anticipation of a particular Charleston specialty— a hearty and delicious Sunday brunch.
The real issue for most visitors boils down to two questions: How much do you want to spend on accommodations, and in which part of town do you want to stay? Lodging is generally not cheap in Charleston, but because the price differential is not that much between staying on the peninsula and staying on the outskirts, I recommend the peninsula. You’ll pay more, but not that much more, with the bonus of probably being able to walk to most places you want to see—which, after all, is the best way to enjoy the city.