I'll second the recommendation for Hot Tin Roof. Fabulous food, elegant setting. Costly, but exceptional. The dishes I remember were tuna tartar, lobster and jerk shrimp grits with truffle oil, lobster bisque, strip steak with cabernet sauce, and mashed potatoes with artichoke and bacon.
Not as high-end, but really lovely is Bagatelle. While Hot Tin Roof is in a new hotel, Bagatelle is in a wonderful, old Victorian mansion. The food here was sensational, as well. We had the Bagatelle seafood chowder (shrimp, fish, conch in a sherry cream chowder -- fabulous), tostones (fried mashed plantains) topped with creme fraiche and caviar, hearts of palm salad, lobster, Jamaican curry chicken (so good we bought the cookbook), and pecan dolphin fish. So depending on how fine you want the fine dining to be, this might be a nice choice.
Finally, not for the wedding dinner, but if you need a place to have another great meal while you're there, check out Blue Heaven. It's wonderfully funky, mostly outdoors, and while it looks Bohemian, the food is imaginative, fresh, and great. My most memorable meal there was lobster Benedict for brunch -- homemade English muffins topped with a thick medallion of lobster grilled in butter, with a poached free range egg and gorgeous Hollandaise. Another great meal brought us carrot and curry soup with mango chutney garnish and black bean soup followed by yellow fin tuna carpaccio with habanero-flavored tomato coulis andseard deep sea scallops in a sauce of mushrooms, garlic, onion, and tomoto, served with crostini.