I only stayed in Zaragoza for one night, but had the best night of sleep I got in Spain here.
Had a 5th floor room (508) with a large balcony overlooking the market and with a view of the basilica towers. Nice, large, comfortable bed, huge bathroom (by european standards) with a full-sized tub, and strong, reliable Wi-Fi connection.
Location was ideal--literally a stone's throw from the central market, and only about 3 min walk to the Basilica of the Pillar, roman forum, cathedral, etc. Bus 34 from the train station drops you off right in front of the hotel door. Staff was courteous and efficient, and the breakfast (if not anything special) was convenient.
The only off bit was that there was a hint of a funny smell emanating from the bathroom--I just kept the door closed and it didn't bother me at all.

Located near the historic center, including the Basilica of Nuestra Senora del Pilar, market hall, the Ebro River promenade, and a fifteen minute walk to the historic Aljaferia, a UNESCO World Heritage site. Friendly, efficient staff, clean and comfortable accommodations, buffet breakfast included in the very affordable price.