Mount Vernon - George Washington
Arlington National Cemetery - John F. Kennedy and William H. Taft
Washington National Cathedral - Woodrow Wilson
Washington Monument - yes, I know it's closed, but I still want to check it out from the outside.
Eisenhower Memorial - this one hasn't been built yet, but it's already a source of controversy. I don't know the full story but I'm going to find it
James Buchanan Memorial - probably the most baffling site on the list, given Buchanan's historical reputation as the worst president of all time.
Theodore Roosevelt Island! It sounds like the site of a reality show, doesn't it?
The US Capitol - there's a space in the Capitol known as Washington's Tomb; the name pretty well explains what it was built for, though it's not clear if anyone ever asked the guy if he wanted to be buried in the building. Also, the Capitol Visitors Center is home to an item called the Lincoln Catafalque, a platform built to hold Lincoln's casket during his funeral in 1865, and one that's been used in virtually every state funeral since.
White House - two presidents (and three First Ladies) have died there; several others had funeral services in the building, and there are always rumors that a few former commanders in chief are floating around the place in spectral form.
Site of the Baltimore and Potomac Railroad Station, where James A. Garfield was shot in 1881.
Blair House - often used as guest quarters for presidential visitors, it was also home to President Truman for a time while the White House was undergoing badly needed repairs. It was the site of a failed assassination attempt against Truman as well.
Woodrow Wilson House - where Wilson spent his remaining years and died.
Smithsonian National Museum of AmericanHistory - it has or had an exhibit on the presidency, including (I think) a framed piece containing a lock of hair from each of the first few presidents. Now you're just not gonna see that in a lot of other places.
Ford's Theater and the Petersen House - the sites of Lincoln's shooting and death.
National Portrait Gallery, which has a whole set of presidential portraits.