Giostra dell'Orso + Luglio Pistoiese
Ciao again! Since I wrote this afternoon, I was actually looking for the July events in Pistoia - the must-see for you now that you've given me your dates is on July 25 - the
Joust of the Bear in Piazza Duomo, Pistoia's main summer event in honor of its patron saint. You can see some info on the official site here:
http://www.giostradellorso.it/Il-25-Luglio-Pistoiese.asp but unfortunately only in Italian (I'm going to have to write an article for the guide on it since we went last year

and that way have info in English!!) The main competition is teams competing against each other in racing around the sand rink and catching a small ring off a dummy with their lances.... the four sections of town compete against each other, all the trials are added up to make the grand winner, all preceded by grand parade in historical costume. Add it to your calendar for sure, it was a lot of fun to watch!
As part of the July events, there is the
Pistoia Blues festival but I found dates are July 12-15, earlier than when you'll be here. I'll keep looking for events nearby, but definitely you'll have lots in Pistoia and surroundings. Most places organize wine/food events like the one you mention in Montepulciano every weekend so you don't need to go down there for that same type of event (it is kind of far, especially since most events are in the evening). I'll keep looking for other events in Pistoia and around and post what I find back here.
Definitely recommend Prato which is close by (the center is small but the Duomo is very charming and so are the walls). Arezzo is also very lovely, it is a bit further away but if you plan on doing day trips around the region it is definitely doable in a day.