If you like flying toys, I strongly recommend following two places
1. College Park Aviation Museum (admission fee $4, no parking fee)
Wright brothers landed here in 1909, when they tried to sell their first aircraft to US government. You have to see what were the initial military specifications (speed, weight, level of difficulty to operate etc. ) of a flying object in 1909. Did you know that Wright brothers were ordinary bicycle mechanics?
2. Udvar-Hazy Centre Air and Space Museum ( no admission fee, $12 parking fee)
Take the elevator, go to level 7 which is the tower lvel, and see how it looks like when planes land from east, west and south of Dulles airport. Go to level 6, to learn how Air Traffic Controller team work. Go down to level 2, take pictures with the magnificent artifacts of aviation history. Don't forget to learn about SR-71 (Lockheed calls it Blackbird), why it was built, why it was so expensive to operate, why it was phased out, and why US Navy loved it more than US Air Force did.
Get a guided tour or try to attend special event listed at following website
http://www.nasm.si.edu/events/calendar.cfm?month=05&year=2007&prevEvents=No Scott Willy is the most amazing tour guide and an expert on military aircrafts. He was there last night for "A night at Air and Space museum"
