Should you ever come to DC for an extended time, consider exploring the overlooked southeast section of the city (in the back ground of the photo on the left)
That battle ship you see is parked at the Navy Yard where the Secretary of the Navy lives. The ship is open for tours and there is a large, very large, Naval Museum on the grounds. It's free of course.
About two miles away is the Frederick Douglas estate which is a national park and open at no fee to the public. It has some of the best views in the city. The national arboretum is out on New York Avenue and is acres and acres of flowers from all over the world.
Closer into the city is the national aquatic gardens which is an amazing place. All of these places aren't visited much (Compared to the sites downtown) and are well worth the trip
Below is a photo of our new base ball stadium