Haven't flown the E175 yet, I think. Could be wrong.

I've always imagined RJ's on short routes such as DCA-PHL/JFK/BOS, maaaaybe DTW. I've always seen IAH-DCA as a longer midcon (it is almost 4 hours, after all), and thus deserving of a 737, at least. I know IAH-IAD have gotten RJ's for many years now, but DCA has always had a more "premium" feel to it. Disappointing, frankly.