I just tried Bodega in Georgetown (M Street) and it was great (more tapas, less wine bar). Had a variety of tapas including; tortilla espanola, scallops, piquillo peppers stuffed w/ braised short ribs. Everything was delicious, and surprisingly authentic- the tortilla was the best I've had outside of Spain. Didn't check the wine list as we went straight for the sangria- which is good as well, not too sweet. Highly recommend it, great service, great food, only tiny drawback is that the tables are pretty packed together.
Agree...really like Bodega for tapas. I'm sure many will recommend Jaleo for tapas but I'm not a fan. I really like Cava and Zaytinya for mezze.
My favorite wine bar is without a doubt Proof in Chinatown...not exactly "casual" by some people's standards but excellent wine, food, and ambience (not tapas-style though). Their octopus salad is incredible.
Vinoteca on U Street is a great casual wine bar...I particularly like the tuna sliders.
I love Bardeo in Cleveland Park...great wine and tapas.
Enology is a wine bar (Cleveland Park) that serves their food tapas-style. I've only ever had wine flights and cheese there so not sure if the food is good.
There's also Sonoma wine bar in Capitol Hill. I work 2 blocks away so I've been a lot--in fact, too much--need a break. I tend to go there more for the wine than the food, but I might be a bit biased since I'm a little Sonomed out.
Great list! I'd all add the obvious - Cork - on 14th street south of U. I'm not personally a huge fan. The wine list is great, but I've found the menu to be expensive and the place is often just mobbed.
In the same neighborhood, Bar Pilar, which is VERY laid back and casual, has an amazing menu of small plates. It's not a wine bar, though you can buy wines from a brief list of decent choices. Go for the food. You won't be sorry.