Xi'an: Rongmin International Hotel
I stayed there recently. 5min to Bell tower, great location, excellent breakfast, and I get a really good rate. About 400 RMB per night (including breakfast), checkout time is 2pm only, which comes in perfect for a late-day flight.
Also only about 10 minutes from the "bar street" in Xi'an. Would definitely recommend to stay there. They do speak good English, the hotel is new, (lower) 5* quality, and there was really nothing wrong about it, especially for the rate I got.