We went last year too and had a great time, we have to go back to see the rest of it. Spent just about a whole day in the Air & Space Museum esp. after I found all the WWII planes
We got stuck in the rain one evening at the Lincoln Memorial and didn't leave until after it was dark. As we were walking back, it was still kind of misty and my daughter says "Who are they?" I looked around and saw we were in the middle of the Korean War Memorial- wow.
We also took a ride up to Baltimore and saw the O's beat the yankees.
Lots of walking though