Focusing on purely seasonal offerings which never stay on the menu longer than three months, 
Circa 1886 (149 Wentworth St., 843/853-7828, www.circa1886.com [1], Mon.–Sat. 5:30–9:30 p.m., $23–32) combines the best old world tradition of Charleston [2] with the vibrancy of its more adventurous kitchens.
The restaurant—surprisingly little-known despite its four-star Mobil rating—is located in the former carriage house of the grand Wentworth Mansion B&B just west of the main College of Charleston campus. It is now the playground of Chef Marc Collins, who delivers entrées like a robust Beef Au Pivre and a shrimp-and-crab stuffed flounder, to name two recent offerings.
The service here is impeccable and friendly, the ambience classy and warm, and the wine list impressive. Be sure to check the daily prixe fixe offerings; those can be some great deals.
Links:
[1] http://www.circa1886.com
[2] http://www.moon.com/destinations/charleston-savannah/charleston