First Time to DC
I'd second Jaleo for tapas...really nice and reasonable prices. Since it's tapas, you can keep to almost any price range you want. Decent list of Spanish wines, too.
I also liked Ray's the Steaks, but I do think it is overrated. Service is slow (at best). However, for the price, you do get good steaks & sides.
To stay downtown, I'd hit the Chinatown area, but not for Chinese. Matchbox has great pizza, but their highlight is their mini-burgers, which are amazingly good. Very nice wine list, too. It's a VERY reasonably priced meal. In the same area, for a splurge, hit up Zengo, which is the only fusion restaurant that I think actually works. Zola is great for drinks and has a clever menu. Also nearby, if you like Middle Eastern, go to Zaytinya for the beautiful architecture as well as the food of one of DC's most well-known chefs, Jose Andres (who will be on Sunday's Iron Chef)!
I cannot more highly recommend either Ray's The Steaks -- just over the Potomac off Wilson Blvd. -- or Ray's The Classics, three blocks north of the Silver Spring Metro stop on Colesville Road. Both owned and run by the same guy, Michael Landrum, who works magic with beef. Forget Smith & Wollensky's, Morton's, Peter Luger ... The Ray's places have the best beef I have ever eaten in my life, and that includes all the gorging I did on the grass-fed lomo down in Argentina.
I just ate at the Silver Spring spot last night and ooooooooooooh was it ever good.
Seared scallops, veal sweatbreads, amazing hanger steaks, and a mushroom "ragout" which wasn't a ragout at all -- at least as I understand the term -- but rather some sort of cooking process that reduces the mushrooms to leathery little hunks of umami-licious goodness. I wanted to rub it all over my face, and would have, if I weren't in public.
There was also a staggeringly good pinot noir that I will not tell you about, because I am incredibly selfish and I don't want it to be gone the next time I head back.
For cheap eats, you can't beat Pho 75, right next door to Ray's The Steaks on Wilson Blvd. Six or seven bucks gets you the best vietnamese beef noodle soup anywhere near the city.