D.C.

I found myself with several hours to kill before flying out of Reagan National, and I was able to quickly take in a few of the local attractions.  The most frustrating part of the experience was being able to drive within a stone's throw of almost all of the landmarks (except the White House - can't get too close to that in a car), but NOT BEING ABLE TO PARK!  If you ever go to DC, take some time to learn about the public transit system, or just plan on biking/walking around the city.