It seems few queries draw as wide a variety of answers as the one above.
In the few months that I have been researching great meals in Rome, Tuscany, and Venice, I have heard and read more that 100 different answers to it.
One particular place that I have not heard mentioned as much as I though is Gambero Rosso in San Vincenze. They got a nice write up in Gourmet's Italy issue and seemed worth the long drive from Cortona, and we may just do it anyway.
Unfortunately, we are travelling during the beginning of July. Not the height of gastronomic abundance I know ...
So is there something, like a balsamic producer in Modena or a bakery in Siena, or somewhere, like La Giostra (not even sure if I got the spelling right on that one) in Florence, that we just cannot miss?
And, btw, after countless searches on this and the international board, I just want to say a HUGE tyvm to all who posted. You are all much appreciated.