<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by debua1k:
I have booked a capital tour with my senator as well as a Supreme court tour, BEP tour and Library of Congress tour. We plan on seeing Mt Vernon and the Smithsonian.</font>
Well... the monuments: Jefferson, Lincoln, Washington... but maybe that goes without saying.

FDR monument is pretty interesting, too. Korean War Memorial, Vietnam Veterans Memorial. Leave about a half day to walk among the memorials listed above-- and do it on a day when the weather is nice.
Of the Smithsonians, the Air and Space Museum is a must-see.
Arlington Cemetary has a changing of the guard at the Tomb of the Unknown Soldier every hour on the hour, and the cemetary is open until about 5. You can see the JFK Eternal Flame, and also the monument to Women in the Military.
The Iwo Jima/Marine Memorial is nice to look at, and gives a great view of DC.
Know that Mt. Vernon closes a little early: I think the last entry is at 4, and you have to leave by 5.
Hope this helps!!
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Re. DC Happy Hour, Alysia's suggestion sounds fine to me. Thoughts???