Day trip to Siena and other Tuscan town(s) using Public Transport from Florence

You should look into a tour company that does small groups. Artviva has a couple tours that goes to Tuscan hill towns and/or wineries. And I'm sure there are other companies as well.

Hi, Abhinav. I know you've already had a few questions on this forum about your trip. If you are also using Rick's Italy book, then see short wine-tasting classes at the Tuscan Wine School, described on p. 636. My recommendation is NOT to make a special wine tasting side-trip, given your limited travel time. Siena is worth spending a full day and good wine should not be hard to find with any of your meals.

You won't have time to do Siena and Chianti on the same day using a bus. The bus takes 75 min and Siena will take most of your day as there are numerous things to see. Also the bus takes the freeway, not the Chianti Road, therefore you won't be able to stop along the way.
If you rented a car you could potentially drive back from Siena to Florence in the afternoon using the Via Chiantigiana (Chianti Road) or SR (Strada Regionale) 222. It takes longer however since it's curvy and once you add some stops at wineries along the way, it would take you a few hours to drive between Florence and Siena. If you did that you would have only a few hours in the morning to see Siena, before heading back through the wineries in time before closing time, and frankly I think Siena deserves a day, not just a morning.
I think if you like wine you either ditch your trip to Pisa/Lucca completely and do the Chianti instead, or drink at an enoteca while in Florence. The wine shop of Fratelli Zanobini on via Sant'Antonino (almost at the corner with Via Dell'Ariento) is a good place for a quick glass of Chianti.

Hi Abhinav, From Florence I took a most memorable all day bus tour Best of Tuscany (do not recall name of company) including lovely Siena, wine tasting and lunch at a small family vineyard near San Gimignano, hilltop town San Gimignano, tower of Pisa, returning to Florence in the evening. I think the vineyard is Fattoria Poggio Alloro. Their Vernaccia di San Gimignano was a pleasant white. I liked Siena the most and could spend a day or two if I re-visit Tuscany. Cheers!

Thank you Peter. I will try to google for such a bus tour!

You can easily visit Lucca and Pisa in one day. I did it a few years ago and it worked well. I’d suggest going to Pisa by train in the morning, doing Rick’s walk to Field of Miracles, taking a late morning bus to Lucca, eating lunch in Lucca (several good restaurants from which to choose), exploring Lucca in the afternoon and taking the train back to Florence. Doing Pisa first gives you the option to linger in Lucca, which I find the more enjoyable of the two cities. Since the trains are regional, you can purchase both tickets in Florence and then take any regional (R) or regional veloce (RV) train, but don’t validate the return ticket until you get to the Lucca train station.

Tuscan Wine School is a good way to learn about and sample local wines and olive oils. They have locations in both Florence and Siena, with the Siena location being slightly less expensive. Also, they sell local wines at the Siena location but are not permitted to sell them in Florence. I attended a session in Siena last year and enjoyed it. If you don’t find a wine tour you like, it’s an option well worth considering.