I got stuck at Dulles last week and finally made it to the U-H Center. It's on the eastern side of the runways but kind of a pain to get to from the terminal. It really is a must-see for airplane buffs, though with great looking, unfortunately non-flying, examples of aircraft from the earliest days to a Concorde and a Space Shuttle.

Personally I liked the engine displays best. They have a great display of recips from early ones I wouldn't trust to make my lawn mower go to the last of the monster Wrights and Lycomings, which I guess weren't so reliable either.  The jets are less well represented.  There's also a restoration hangar where you can watch progress on their latest, I'm guessing some kind of Dornier seaplane from the 1930's.

The disappointing part is it's not photography-friendly. It's tons of stuff crammed into a big hangar with planes stacked three-deep in some places - one hanging from the ceiling, the second on blocks lifting it off the floor, and the third nestled under the wings of the second. It's almost impossible to get a clean shot of anything and I tried.

It's sort of free - you can walk in the door for nothing - but parking is $15 and a taxi to/from Dulles will be $20 or so each way. Still, if you're ever stuck at Dulles for several hours, it's probably cheaper than drinking.