I have lived in the District (DC proper) for about 8 years now. I grew up in the area and have lived here for most of my life. Everyone has recommended great places. For about a year I worked down near the Reagan Center and I have eaten at Aria a few times. It’s pretty good. I haven’t had any issues with Harry’s. I think it’s fine for burgers and beer, etc.
As for Jaleo – yes! You can order as much or as little as you would like. The food is always good. I might wind up going there tonight, actually. It’s pretty much all small dishes although I did have an entree there once. The gambas and date fritters are two of my favorites.
There is also Oyamel (Mexican) which is at 401 7th St. NW. It’s about a half mile from the Reagan center, I think. It’s another winner. Entrees run $11-20. I’m not sure how much the tacos de chapulines are but it should be easy enough to hop on over and find out :).