There are so many things to see and do along the National Mall (museum and monuments). Definitely consider some Smithsonian Museums while there.
There is a winery and brewery onsite. The pizza is a must have.
We love the view here, and the beer is pretty good too.
Another great brewery!
Where the Space Shuttle is! This is different than the Air and Space Museum in DC.
If you are looking for some good hikes and want to cross off a national park on your list, this has many trails.