You have no shortage of things to see in DC. The Smithsonian museums are a week’s worth of vacations in themselves. And while you don’t need to pay for tickets, double check the websites for each museum to see if you need to get tickets in advance. We ran into this problem with the Air and Space museum. All the other museums, you could just walk in but they limit the number of people into the Air and Space museum so tickets get booked days in advance. Another thing that will surprise most Americans: you can tour the White House and Capital Building but you need to apply for the tour with your senator or representative at least three to six weeks before you plan on going. But be prepared to stand in line outside, going through multiple security checks.