On my short visit to Washington DC with my husband, I had the chance to run on two days up and down the National Mall. I saw the White House, the US Capitol, the Smithsonian Musuems and Castle, the Lincoln Memorial... Well, everything along the Mall! There were lots of other runners out, too. The area is kept very clean and everywhere you turn, there are picture taking opportunities. So, the week before the marathon, I ran 6 and then 7 miles in Pittsburgh. Then I ran 5 and then 3 miles in DC. This is a low mileage week because I'm running in a marathon tomorrow.
The bike lanes are in the middle of the streets, which actually worked out fine. We biked for hours using the Bikeshare bikes that we found near the National Mall and the George Washington University area where we stayed. We visited the Smithsonian American History Museum and stopped at all of the Memorials. I loved biking and running at the National Mall.
A link to a video of us riding through DC: https://plus.google.com/u/0/110135536727417977639/posts