We're in the same class; see ya there!
Absolutely seconded on JSG's recommendation of Udvar Hazy.
The Spy Museum in DC is pretty neat, too.
The battlefield at Bull Run/Manassas is a good visit.
The battlefield at Sharpsburg/Antietam is a great visit. Of all of the eastern ones, it is literally the most unchanged, compared to the time of the battle itself, so it's easier to envision troop movements and the like if you truck the thing on foot.
The Range in Stafford has IDPA-ish competitions on 2nd and 4th Wednesdays, which I'm starting to do, this year.
http://www.indoorrange.com/