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.

We added a two night stay in Siena on a whim and we were so glad we did! Siena and Villa Montarioso were the highlight of our visit to Tuscany! This hotel was just outside the city (very quite, great views) and very easy to find. This is a great B&B for families -- offering free parking, good sized rooms with cable tv, wifi, private bathrooms and free buffet breakfast complete with the caffe of your choice. The rooms were clean, the epitome of old Tuscany and an excellent value for the money. I would recommend this accommodation and will definitely stay there again when I return to Siena!

The hotel is located in Siena Nord area, with easy access to the highway towards Florence. If you want to visit Tuscany, you definitely need a car. However, i strongly suggest getting one in Rome, because everything is more expensive in Florence than Rome. Once you have a car, this is the perfect hotel for you. It is very new and maintained in excellent condition. Rooms are very large, including bathroom and all the furniture and appliances are or at least look very new. The hotel offers free wifi (although kind of slow), free parking with easy access for the elevator and more important it offers a very rich breakfast, highly unusual for an Italian hotel. Staff is very friendly and speak good English. If you want to visit Siena, but without the car, you can take an hourly bus which stops right outside. Be careful because the last bus from Siena to Montarioso leaves Siena at 8PM. The taxi will cost you 10-12 eur, so it' not that expensive.

We stayed here for 4 nights. It is very central to Siena, the Tuscany wine region and many interesting Italian Castles. The staff was very accomodating. I asked to have a table and chairs but out on one of the beautiful terraces. They were very accommodating. We enjoyed wine out on the terrace at sunset a couple of eventings. The breakfast was very good. We would stay here again.