As for the DC area, there are plenty of places and the price range varies. Here's some of my favorites:
Raku (moderately priced Asian, excellent Sushi), Dupont Circle, DC
Cashion's Eat Place (expensive American), Adams Morgan, DC
DC Coast (expensive American), downtown DC
Jaleo (moderate Spanish), downtown DC
Kinkead's (expensive seafood), Foggy Bottom, DC
Pizzeria Paradiso (cheap Italian), Dupont Circle, DC
Rosa Mexicana (moderate Mexican), downtown DC
Mandalay (cheap Burmese), Silver Spring, MD
Cuba de Ayer (cheap Cuban), Silver Spring, MD
A&J (cheap Chinese, good dim sum), Rockville, MD
Peking Gourmet (moderate Chinese, BEST Peking Duck!!!), Falls Church, VA
Ledo's (cheap pizza) many area locations
Timbuktu (moderate seafood, excellent crab cakes), Hanover, MD
An excellent resource to use is this link to the Washingtonian's best places to eat (links on the top left):
http://www.washingtonian.com/dining/default.asp
Have fun while in the area and if you want more specifics about any of the above or something else you found, let me know.