I think the most interesting Smithsonian Museum we went to see was the Air and Space museum.
They had all the originals and replicas of early flyers, including the plane of the Wright Brothers and the Spirit of St. Louis:
We saw amazing displays of what NASA has built:
And of course, the lunar landing scene:
It's funny, when I see the planes and the incredible things that are launched into space, I almost wish that I was in the Air Force, like my dad.