We just got back on the 14th. We stayed Club Level at the Hyatt Regancy Capitol Hill. With CL we had a complimentary breakfast, dinner appetizers and a dessert buffet. They also always had a small fridge full of water and soda. With 2 adults and 2 teenage boys, it was probably cheaper to do this. I know breakfast alone was $20/pp in the dining room. It was a short walk to the Capitol as well as Union Station. From Union Station you can catch the Metro to everywhere. (We did not use the Metro at all and hoofed it everywhere we went) However, we did eat at Union Station a few times since it was close to the hotel and they have a huge food court to chose from. I know the Old Town Trolley tours has a stop at the Hyatt, so if you were to do their tour, they could pick you up there. We did the night tour with them and it only picked up at Union station.
www.oldtowntrolleys.com I think is the website for them. Call your congressman and ask to schedule a Capitol Tour. They can also schedule for you a White House tour. We called too late and were denied the White House tour, so call early. The Capitol tour is wonderful...then you can walk through the "tunnel" over to the Library of Congress. There is a free tour there too. We really enjoyed the Library. We did the tour at Arlington too and that was well worth the few extra bucks. I can't see walking all of that!
Have a great trip!