Unfortunately, we saw everything there is to see so she has no reason to come back.
We ate at Ben's Chili Bowl. It is as good as everyone says it is. (Especially their cake!)
We saw some museums, including what I would say is the best museum in the city - the Newseum (unfortunately also the only one that you have to pay for). We went to Arlington Cemetery and caught the tail end of the changing of the guards ceremony.
And what was definitely the highlight of the visit, was riding bikes around the monuments. It is definitely the best way to see them - significantly better than walking since it's about an 11 mile loop.