From Florence to Siena and Volterra

Use the Bus.

There is no train service to Volterra...and the bus brings you closer to the city center in Siena.
The bus station is just behind the train station in Florence, easy....

I just visited these two towns a couple of months ago, travelling out of Florence, though I chose to stay overnight for several nights in Volterra. Siena: Yes, the bus. However, do give yourself a bit of extra time to get your ticket in the Florence bus station and find the bus. (The Siena train station is not convenient to the center of town.) However, to get to Volterra, after much research, I chose to take the train from Florence to Pontedera (regionale, approx 50"; buy ticket from machine in the Florence train station), then a bus Pontedera to Volterra (in Pontedera it's across the street from the train station). The total travel time, including the 20" or so to change from train to bus, was about 2 hours. You can buy your bus ticket on the bus in Pontedera. I believe it was 6 euros. There is also a train/bus connection from Florence to Volterra through Colle de Val D'Elsa (sp?) I strongly suggest going online on trenitalia and on sita.it, and looking at the train and bus schedules when planning your Volterra roundtrip; you may choose (as I did) to go one way through Colle and the other way through Pontedera, depending on the timing. Both websites are fairly easy to navigate. In Colle, the bus area is, again, across the street from the train station. And Volterra is SO worth it! What a magnificent, beautiful, friendly, artistic, historic town, with many fewer American tourists than one might imagine....maybe because folks are a bit daunted by having to make a bus or train change??

Thank you for the responses, much appreciated.

Would it be too ambitious to try and do both in one day? If yes, which would you choose, and why.

You could do both with a car, but with buses it would be challenging and you would be left with little time in each place. Which one to choose is a matter of personal preference. Volterra is a small town, Siena is a city, albeit not large. Siena has more things to see, so if I personally had to choose one of the two, I'd probably go with Siena.

Thank you Roberto, that is what I was thinking as well.