I need to look up all the names of them but there are many to choose from. Any ones you loved and why? First trip out to DC so planning two days of fun to take a tour there and visit a museum. I heard the zoo is free but will prob depend on the weather in terms of comfort! We are making other stops too in Gettysburg...Lancaster(I want to do an Amish tour) then up to visit rel. in Philly. thanks for any suggestions. I will also use tripadvisor.