Oooh...that's an easy one:
The appropriately named Baccanalia Restauarant. You can read about it here. (There are other more casual places under the Star Provisions label - click on the link for Baccanalia.) It is considered one of the, if not the, best restaurants in the city.
http://www.starprovisions.com/
Another good choice is Rathbun's (Kevin Rathbun, the chef, recently won an iron chef competition against Bobby Flay.) Rathbun's and Krog bar are two of my favorites.
Here is the website:
http://www.rathbunsrestaurant.com/
And right next door is Krog Bar - also owned by Rathbun - were you guys can have a drink first. Its a cute little wine bar with spanish tapas.
So my first choice would be Baccanalia - truly not to be missed - and Rathbun's as the #2.