Going to DC for two weeks in July and have rented an apartment, so will be able to cook most vegan needs, but looking for a few nice vegan restaurants for lunch or dinner. Any help would be appreciated.
I just moved from D.C. to Los Angeles a few weeks ago. My absolute favorite there is Cafe Green http://www.happycow.net/reviews.php?id=24179, it's fully vegan and they have some amazing food! I'd recommend trying the mac and "cheese" dish first (and say yes to the cornbread option!) It's right in Dupont Circle, just a few blocks from the metro, and they have an outside patio which is perfect for the summer.
If you have a car during your stay and are looking for more options outside of metro range just let me know and I'll send you some more. Have a great stay!