What are some fun things to do/good restaurants in Washington DC?

For my birthday, my boyfriend is flying me up to to visit him at Ft. Meade, MD. Since DC is just a short drive away, we plan to spend a great deal of time there sight seeing and whatnot. I've already contacted my senator and got a reservation for a White House tour and I've listed all the monuments and museums I want to go see. But I'm looking for some other things to do and some good restaurants. Any suggestions?