Just to add my +1 about visiting Udvar-Hazy.

And a couple of additional points:
1. Museum admission is free.
2. You need a quarter to use the locker, but it is returned when you empty the locker.
3. The shuttle bus operates every 45 minutes on weekdays; and every 60 minutes on weekends/holidays. See the schedule at: http://www.metwashairports.com/dulle...ta_bus_service
4. There is a MacDonald's operated food court at the museum, including a McCafe.
5. Parking charge increased recently from $12 to $15 - so take the shuttle.

PM me with any questions.