Sorry I'm not listing many for your favorites (not into French or Japanese) but here goes for places not yet mentioned:

- Old Ebbitt Grill by the White House (continental) has nice ambience
- Cactus Cantina and Tequila Grill are good choices for Mexican
- Banana Cafe is good for Mexican & Caribbean (Cuban, Puerto Rican) fare
- Lauriol Plaza in Adams Morgan is nice (more Latin food!)
- The Little Fountain in Adams Morgan (continental) always had a nice cozy atmosphere
- Tony Cheng's in Chinatown for seafood or the "mongolian grill"
- Bobby Van's for steaks

There's plenty more... do you want to say more specifically where in DC you'll be? That might help narrow down some choices. Happy dining!