I can't tell you where the game stores are...
But if you like museums, you can't find 2 better cities to visit here.
NYC has the MOMA, and DC has the Smithsonian- the US's equivalent to the Louvre or the Hermitage, and that's just for starters.
In addition, Monty Python's Spamalot is on tour, and I KNOW its going to be in DC at some point. It may also be showing in NYC. If you enjoyed their Holy Grail you'd enjoy this- and no, its not a word-for-word recreation of the movie. It IS hilarious.