I didn't eat much at nationals... I think I bought an ice cream once. Most of the stuff I ate I bought at my hotel, because the food at nats was so expensive.
At NYC, there was actually some pretty good food. There was a nice deli nearby with a great selection of things to choose from. If that doesn't work for you, there's several other Columbia dining places, although I didn't go to them. And of course, there's the thousands of restauraunts on Broadway.
Patrick