On our first day, we went to the Smithsonian's Air and Space Museum at the National Mall. In my honest opinion.. This museum is very outdated. Yes, they have an amazing collection at this museum, but the exhibits and museum itself need an update.
I am thinking about flying out of Dulles. Flights don't leave for the west coast until like 5:30, so I could get in a full day at Udvar-Hazy. Other than I'd have to pack my luggage around. Do airports still have lockers?