The kids and I went on our second field trip to Washington D.C. last November in the same number of years. I didn't figure this would be a problem...even if you visit the same places, there is always more to see than you could ever squeeze in with one visit. We did stop at a museum we hadn't seen the first time called the "Newseum" and BY FAR it was our very favorite. It was full of just about every newsworthy event...newspaper and magazines, pictures and memorabilia.
Here is a picture of a piece of the Berlin wall.