The aide at our Congressman's office is arranging our tours of the Capitol, Library of Congress, and The White House. I contacted Arlington Cemetery and was told that once we show them our Handicapped Sticker they will issue us a special pass allowing us to drive to the key areas.
We'll use the Metro to get around within DC, understanding that we may have to allow extra time for the elevators. We plan to visit the Air & Space Museum and American History Museum (both are part of the Smithsonian) on Sunday afternoon. Monday will be the Capitol, Library of Congress, and Arlington Cemetery. Tuesday is The White House (depending on what our congressman's aide can arrange), the Holocaust Museum, and the National Cathedral.
We plan to have our midday meals at cafes/cafeterias, etc. near our scheduled stops. Evening meals will be at "driveable" places in or around DC. We generally prefer regional specialties to fancy places and there's a good selection on Roadfood.com and Washingtonian Magazine. Should be great as long as the summer heat isn't excessive.