When are you coming? If it is soon and you need to check immediate availability, take a look here.
We've personally stayed at the hotel Roma right next to the Square of Miracles and the Leaning tower. It was quiet, modern, breakfast was good and very convenient as it was close to everything, including the San Rossore train station for moving about.... this is important if you won't have your own car.
The Villa Corliano looks like a very nice, historical villa and hotel and is in San Giuliano Terme, about 7km from Pisa. Will you have your own car to get there? It does look like you can reach it by bus from the Pisa airport if you don't... so if want to stay out in the countryside, it looks like a nice place. It does matter when you're coming, as they seem to be closed from mid November through Easter of every year.
you're welcome! then the hotel Roma should be perfect as it also offers parking.
Also know there is free parking near the hotel, a little before you arrive on Via Diotisalvi ;-) that way you can avoid paying either at the hotel or in the two nearby paid parking lots (which are ones used by visitors to the main square for just a few hours).