Sunday night near McPherson Square
We'll be visiting from San Francisco and won't get into D.C. until 8ish on Sunday. What's good and open late near McPherson Square? Nothing complicated or fancy.
We're willing to walk 15-20 minutes nearby but will probably be too tired to hop on the metro again.
Define "complicated or fancy." Acadiana would be a few blocks east on K, and they're one of the few open on Sunday. After Sept. 21, Central will be serving on Sunday nights. and for comfy French bistro, Bistro D'Oc wouldn't be an awful walk. It all depends on how far you're willing to hoof it.
Agreed Brasserie Beck might be a good option for you as not much is open on Sunday night, I am not even sure if Acadiana is or not. The appetizer portions are big, the moules and frites very good, and the beer list is amazing.
Zengo is a bit of a walk but not too too bad and they are open, but they might fall in the complicated and fancy... You are in a business district and just not a lot is open there at that time that is low-key. Perhaps if you wander down to Chinatown? There are threads you can search on that.