Have stayed in both the hotel El Coloso and the Best Western Arosa this year. Both are central and should fit your requirements. The El Coloso is the nicest of the two and laterooms.com will find you a good price, as will octopus. It is smart, modern, good value, a good breakfast and a small bar. Only draw back is that it is next to the start of the red light district and every night on your return you have to dodge the touts for the various venues in the streets just a little further on. Other than that, just a short walk to gran via and all the central attractions. Close to the metro. It's on a side road so is quiet at night, and there are plenty of small bars/shops and restuarants nearby.