Can we assume that the OP will be using trains between the various cities? If there's a rental car, I would highly suggest going to some smaller towns or even rural castle type hotels. Also, if the OP plans to return to Italy, I would suggest focusing on a smaller region on this trip and for example including Pisa, Luca, and Sienna if there's interest in Tuscany, while a foodie should include Modena and someone interested in history might add Bologna.