We loved our stay at Bonello. The location is beautiful (it was also a bit farther than we expected - if you think you've gone too far, go another ten minutes and you'll find it!). We did one of the hosted dinners, which ended long after the food was served, drinking grappa and talking with new friends - and there was more food than I could ever have eaten; they were also very helpful in making me a vegetarian option.
Luca is the real gem - very friendly and knowledgeable, he has lots of resources for visitors and the map he gave us was invaluable.
You are staying in the middle of the country, so expect a fly or two. But the room and bathroom were large; and the fridge was stocked with wine glasses and a wine opener, which was perfect after a day at the enotecas.
We hope to come back to Tuscany someday and we would definitely come back here.