while you are in DC area, take time out to go to the Pentagon and go the 9/11 memorial there. I didn't know it was there until I was in DC for work. It was really a thought provoking memorial (especially for someone who works for DoD)
Oh yeah, if you want to do tours of Capital, White House, etc, get with your home state Congressman's office. They can set some of that up for you, so you can go a bit more in depth. I wish I would have had more notice of my trip, so I could have done the tours that are set up by my Congressman's office.
there is an RV park in MD that everyone seems to recommend for touring DC. figure out the metro and use that to your advantage.. much better than driving and trying to find a place to park..