Some sightseeing advice and tidbits from a Maryland-suburbs-of-DC native:
1. They got rid of the Foucault Pendulum in the Museum of American History
But they do have Stanford's autonomous car from the DARPA Grand Challenge, as part of the "Science in American Life" exhibit
2. The legs of the lunar module on display in Air & Space are fake. How can you tell? the real ones would collapse in 1g. Air and Space does have the real SpaceShipOne, however.
3. Best food at the Smithsonian: Museum of Natural History. They also have a little game where you can simulate smashing asteroids into the Earth (and some pretty rock called the Hope Diamond)
4. Best view: The old post office tower (NOT the Washington Monument). Gigantic windows, and zero crowds.
http://www.nps.gov/opot/planyourvisit/index.htm
5. The rule for Metro escalators is walk on the left, stand on the right. Just do it.
6. And the next time you fly into National, sit in a left hand window seat. If the wind is right, you fly in down the Potomac, past all the monuments. It's an epic view.
See you guys tomorrow!