these are the big annual events - for local ones, wait till you are in the area
Ciao Matt,
It is likely you'll find local events in Siena and Montecatini going around on that weekend that are never publicized well ahead of time on the Web - many
sagre (local festival that usually revolve around food) are still today only "announced" and publicized through posters hung up around town a few weeks ahead of time. Here in Florence as you walk around you see these billboards with these posters that say
sagre are going on in nearby towns in the province. For these you really do have to be here in the area to know what is going on and decide.
The big annual events which you see on our events calendar are:
June 16 and 17 in Pisa - feast for the city's patron saint San Ranieri - the
Luminara and Regatta.
June 18 - the
Joust of the Saracen in Arezzo - yes, you do need tickets - the
official site is only in italian but basically starting March 7 you can email or call to reserve your tickets. Cost of tickets are still those for 2010 and need to be updated.
June 18 and 19 - in San Gimignano, the
Ferie delle Messi takes place over both days that third weekend in June. You can read more by following that link.
On June 24, you could come into Florence and see the final match of the Calcio Storico (hoping there are no problems this year with its being cancelled altogether like last summer). You would also need tickets for that but those are available closer to the date and online.
A car is definitely practical if you do want to attend some of these events. From Montecatini, you can easily get around to Pisa, Florence, San Gimignano.... the only event that is further away and would take longer to get to would be the Joust in Arezzo (like an hour and half drive each way). Even if you just want to go to these towns and walk around without seeing the main event, moving around with a car would still be practical. If you don't want to drive, Montecatini Alto is right above Montecatini Terme where you'd be on the train line Lucca-Florence which would make it easy to get to Pisa and Arezzo by train (with a train change in between). San Gimignano would require more planning but still doable.