Travel from Florence, Italy to San Giminagno

Drive. Pick up a rental on the outskirts of Florence to avoid all the ZTLs.

I'm a public transportation person, like to relax on the train.
You can take the train for about 1 hr 45 minutes - looks like there are several trains per day.

The Poggibonsi-San Gimignano train station is in Poggibonsi. You can also get to Poggibonsi by bus, which is what I did. In either case, you must then take a separate bus from Poggibonsi to San Gimignano.

It depends on you. A car is a great way if you enjoy driving and wish to see other sites. If a car, the pick up outside of Florence. A car allows you to explore the areas between and around your destination. If going point to point, which I do not think is a good idea, talk trains or buses.

You can go by bus. First to Poggibonsi, then at Poggibonsi there is another bus that goes up the hill to San Gimignano.

Poggibonsi can also be reached by train from Florence, but the train takes a bit longer because the railway goes around to the west to Empoli first then down south to Poggibonsi the railroad follows the flat valleys (trains don't do hills), while the bus can go straight through the hills on the freeway, so it's more direct.

A car is useful if you want to couple the trip with some other place around there (maybe a detour by the Chianti road on the way back) or some other town around the area. But if you go strictly for San Gimignano, then the bus is more efficient because renting a car for a day involves also a lot of wasted time getting to/from the rental office, finding your way out of Florence to/from your destination and some bureaucratic steps for pick up/rental return paper work.

There are two possible answers based on your intent. If you are just trying to get from point A to point B, especially in the least amount of time and spending the least amount of money, public transportation (train/bus) is your answer. However, if you'd like to see some of the most beautiful Tuscan scenery with some wonderful opportunities to explore small towns, then renting a car would be the answer. You could drive down SR222 through Greve, then across to Castellina. There's a lovely mountain road (SR429) that drops down into the valley, then through Poggibonsi. Out of Poggibonsi you catch SR1 to San Gimignano.

Many thanks to all of you for your responses. We ended up taking the bus from Autostazione to Poggibonsi, then transferring to San Giminagno. It was a nice drive. However, dealing with the bus system & not speaking Italian was a bit of a challenge at first, as to be expected. Very important lesson: ALWAYS HET YOUR TICKET VALIDATED ON THE TICKET MACHINE ON THE BUS!! Two fellow travelers were fined 60 euros each, as we got off the bus, because they did not know to get their tickets stamped. Stupid rule, makes no sense, but lesson learned.