Ooh, a thread with which I can relate as a near-vegan (I eat goat cheese on occasion...).

Before I hit the road, I always check http://www.happycow.com, and it has done me well. I even found vegan grub in Pensacola, FL. My personal favourites are:

DC:

Asylum- A mainly vegan biker bar with an amazing brunch.
Sticky Fingers- A fully vegan bakery with killer brownies and cookies.

NYC:

Red Bamboo- I am only familiar with the Manhattan location, but I always eat enough to make myself sick, as everything is good.