I had a totally awesome time when I was in DC last year. I nearly burst into flame from the heat, but it was bearable. I saw five baseball games as well - fortunately, my seats at Nats Park were right under the middle deck, so I was in the shade the whole time I was there
. I even got to see a brawl! (Cubs started it.
I think my favorite non-baseball thing that whole week was the National Air & Space Museum. You could spend a whole week just THERE.