Seafood in DC
Pesce is usually quite good....although it has been cited for inconsistencies over the years. It is quite small and not built for comfort.
For a more romantic dinner with a seafood emphasis, try Sea Catch in Georgetown. For a fabulous meal in comfortable surroundings and the best seafood in DC (in my humble opinion), get reservations at Kinkead's on Pennsylvania Avenue.
You won't regret it.
I agree with Jason's assessment. Good food; bustling atmosphere; I don't think it takes reservations (at least it didn't used to)--not sure if that's the atmosphere you want.
If you search this page for "Dupont Circle," there's a previous discussion earlier this month on Pesce and other nearby restaurants in Dupont Circle.