We're going to be in Arezzo for a few days in July and are looking for a few good winery tours. Unfortunately the days available for us are Saturday, Sunday and Monday(going to chianti). We are willing to travel as far as montalcino.
Have a lovely time in Arezzo! It is where my relatives are from, I spent two weeks there last summer and am going back for four months (study abroad) this fall! This winery is not in Arezzo, but is not too far--Baracchi Winery. It is near Cortona, a family owned winery/restaurant/hotel. The tour was lovely and professional and the wine was delicious. (These photos may give you an idea of what the tour is like: http://www.facebook.com/media/set/?set=a.135681029781743.23829.113985878617925)
Thanks for the great sites, Baracchi was already on my short list as it's in the vicinity of arezzo.
Sorry I can't help more, that is the only one I have personally visited, but I know there are some other great ones in the area too. Loved my time at Baracchi though. (I've also been to my cousin's vineyard but that's not exactly a winery haha. He just makes 200 bottles a year for friends and family in his backyard. Oh, to live as an Italian!)