What too do in DC!?!?!?

Ok, so nxt week Im going to Washington, Dc...again. The first time I went which was a couple of weeks ago It was on a school trip and I went to the White House (inside2), Lincoln Memorial, Smithsonian of Art, Capital Building, Supreme Court, Washington Monument, Jefferson Memorial, Holocaust Museum, Nam Veteran Memorial... And we stayed @ The Hotel Harrington so places around there, so what do u suggest3 me to this time now that im with family, i already know i want to go to the zoo...lol and to the shopping district, greens burg i think thats what its called and six flags