DL: Club 33! Understanding that this is not always an option, we like Cafe Orleans and the Plaza Inn. We avoid Blue Bayou and the little German place (blanking on the name) over by Pinnochio.
DCA: Vineyard Room for fine dining, Taste Pilot's Grill for something more casual.
In the hotels and DTD: Ralph Brennan's, Storytellers and Hook's Pointe.