We had a great trip. We spent between 5 and 7 hours every day, for four days, seeing the sights or getting from one location to the next. We used the train system exclusively and it was an excellent way to get around. We both purchased SmarTrip passes ($35 each) online, at home. You just place them on the turnstile. We took the train more often than I can remember and, when we were done, we still had about $11 on the cards.

If you want to take serious photos, I suggest you bring a tripod and have plenty of time on your hands. These pictures are hand held snapshots. Most indoor photos must be made without a flash, and some of the interiors were very dim. I had to discard a number of them and even some these are poor quality. Also, quite a few places don't allow pictures (Star Spangled Banner, Constitution, Declaration of Independence, etc.).