TRYP Ambassador was clean and comfortable a minutes walk to the Opera house, 2 mins to the Palace and 5 mins from everywhere. We'd stay there again for the convenience. The hotel staff were very friendly and helpful. Book a taxi back to the airport through them so you don't get ripped off like we did. Taxis from the airport add about 14euros surcharge, then an extra 7 or 8 per bag. so 30 turned into 50euros!
I also thoroughly recommend the Tapas tour and the Segway tour but book those online before you go. Do the segway tour as soon as possible so you can see the area you'd like to visit after. We went everywhere :-) Take gloves as your hands get chilly.