We spent 2 nigths at the Villa Montarioso in Monteriggioni in april, and our experience had plus and minus points.
Positive points: confortable bed, spacious and very clean bedroom and bathroom. Nice shower and amenities, towels absolutely clean and soft. The breakfast is´nt not special if you are expecting tuscan specialities (You wont find it there). The attendant was very warm and gave us the mais instructions when we arrived ... even so, after 5 PM, they missed and the hotel was totally in the guest´s hands.
To find the address is dificult, and the hotel´s web site dont provide enough information, you need a GPS. In its neighborhood does´nt have shopping area, or at least, a small shop...you need a car for everything.
Don´t be surprised but the hotel is located in a complex composed by a catholic seminar, a church and another historic building mannaged by the religious. I think that the web site should inform this particularity.