McCormick & Schmick's has some of the best seafood in the city in an upscale atmosphere. Eating a full meal here can get very expensive, very quickly. However, if you go during their amazingly cheap happy hour, you'll get to sample the menu and still have Metro fare home.
The happy hour lasts from 3:30-7 and 10-11 on Monday—Thursday, and 3:30-7 on Friday's. Apps start at $1.95 for munches like hummus and only go up to $4.95 for seafood apps like crab cake sliders and calamari.
You can't beat that, especially considering that this restaurant is one of DC's best.
Pros: Insanely cheap happy hour deals, amazing food quality
Cons: Expensive unless you go during happy hour