The National Aquarium hasn't changed much since my last visit, but they are building a new section, curiously focused on Australia. The Atlantic Coral aquarium alone is worth the stop in Baltimore. A dolphin calf was born the day we arrived, so there were no shows for the weekend. C'est le vie. While in the inner harbor, we also ascended the Baltimore World Trade Center for a bird's eye view of Fort Henry.
Kristan wanted to tour the USS Constellation, which was surprisingly enjoyable. From outside, it doesn't look like you're missing much not going on board, but the museum aboard the restored ship covers a wealth of history.
Before heading to DC, I climbed the stairs up the original Washington Monument for an excellent view of the city. Very reminiscent of the Compton Hill tower, except the graffiti inside was often political. Of course, I had to visit Legal Seafood to begin a week of good food.