mall and to all the main monuments. No reason to pay for a dorky bus tour. I'd use that and see all the major monuments and prioritize the museums. Holocaust, Air & Space, Amer. Hist, Art, Newseum would be on my list. Capitol and Library of Congress and Ford's theater are great too. 2 days isn't a lot so probably not time to do much more than just the downtown area --- prioritize and you'll get in the best stuff.