I always stay in Crystal City when visiting DC because of the great hotel rates here on the weekend. This Residence Inn, together with the Renaissance next door (same building), are the two newest hotels in this area (opened 2011.) The great reviews here are accurate and I would stay here without hesitation, especially for a longer stay, when you can take full advantage of the complete kitchen, free breakfast and weekday dinners.
--clean, modern, functional rooms with full kitchen, free wired or wireless HSIA, room safe.
--large TV channel line-up with HD programming
--free shuttle service to DCA and CC Metro every 20 mins till 11pm
--extremely quiet despite being next to DCA; did not hear any planes over a 5-night stay, though I heard the train a few times.
--abundant restaurant within 1 mile radius of hotel: you can walk or be shuttled to 23rd St and Crystal Drive
--very friendly and polite staff; I especially appreciated Tiffany (front desk + shuttle), who located a lost item miraculously and promptly mailed it to me at home; she is a wonderful staff member!
--large fitness center shared with the Renaissance, always open, rarely crowded
--nice hot food selections at breakfast and dinner time
--dining area can get quite full at breakfast and dinner; I suppose you can always take it back to your room if there are no tables.
--no mugs at breakfast, just styrofoam cups, even though there are real plates and silverware
--while weekend room rates are super, the weekday rates are in the $200's, still lower than downtown DC