I went down to DC with my daughter and her girl scout troop today - we had a tour of the White House, which was pretty neat. We had a bit of excitement at the end of the tour - outside, someone jumped a security fence and we had a lockdown for about 10 minutes while they sorted that out. It ended quickly, and we headed off to the National Archives - I had no idea that they had one of the 4 copies that were produced in 1297 (well after the original, of course). That was neat. We didn't have long there, but it looks like it would be well worth a full day.
In between the White House and the Archives, we went to lunch at the old post office, which is a beautiful building. You can go to the top of the tower, which provides a great view - here's a camera phone shot of the capital I took from up there:
Earlier, I took this shot of the Washington Monument from the grounds of the White House:
All in all, it was a nice day downtown.