Let me second the many nods for Peninsula Grill. It is my favorite restaurant in the world (and that's saying something!). It's a clear 5* place, very elegant, and an old-world 1950s feel. I don't say it's the best food anywhere, but everything is well done, and if you like this type of fine-dining southern atmosphere, it doesn't get any better overall. It is also known for its excellent champagne by the glass list. The hotel attached to this restaurant is also my favorite in Charleston (Planter's Inn).

Related, if you like classic, old-world hotel bars, I think two of the best in Charleston are the Thoroughbred Bar at Charleston Place and the Barbados Room at the Mills House Hotel. I've never stayed there, but I take it that the Charleston Place is one of the best hotels in the city (it's an Orient Express hotel I think). I stayed at the Mills House recently, and it has some charm and nice public spaces but is not in a top-tier hotel league. Very worn down and no service to speak of. But the fact that the Barbados room is there is a huge plus. Got it for $91 on priceline on a weekend.

For seafood in Charleston, I like Hank's the best - far superior to Hymans, in my opinion.