Good restaurant for a fun business dinner

Hi, I'm making my annual trip from San Francisco to D.C. this September for TCT - a huge medical conference held every year - and I know I should make reservations soon if I don't want to find it impossible.

We use this conference each year to throw our big company dinner for the 10 or so doc's we work closely with. It's a very wealthy group - but not stuffy, and we like to go somewhere that everyone will have a really good time (and lots of great food and wine). The reservation will probably be for 15 or 20.

Last year we did Galileo. Any recommendations for this year? A private room is most desirable - somewhere close to the Grand Hyatt/D.C. Convention center area.

Thanks for the help!

-Kirsten