Let's get a quick list going of people's favorite restaurants in the most restaurant-packed areas of the city. I'll start a couple of these off, and hopefully others will pick up the ball and run with it. I only really eat out in a few areas, though, so I may start off a couple lists with a blank!
My current favorite place in Dupont is just a little lunch place but they make things fresh in front of you, everything I've ordere there has been good so far, and their portions are substantial but not disgustingly huge. The Dutch Mill Cafe, just south of the Circle, has great deli sandwiches, interesting salads and roll-ups, an extensive grill, and also a selection of pastas and sauces, with everything going for about $4.50 - $6.50. Particularly good are the Chicken Tender Rollup, the Fettucine Alfredo with Chicken, the grilled portobello mushroom and veggie sandwich and the Barbecued Pulled Turkey Sandwich. Sure, it's just lunch food, but lunch doesn't have to mean low-quality and mass-produced.
If others start to add to this list, I'll come back and post a real "restaurant" recommendation.