Just want to confirm that I'm on the right track here:

According to the SITAbus (holiday) schedule, we can travel from Florence to Siena at 9:10am, and leave to return to Florence at 6:10pm? Also, I understand that we can buy tickets at the bus station near SMN? Could we purchase our tickets a day ahead? Thanks for any advice...

http://www.sitabus.it/wp-content/upl...enze-Siena.pdf

Yes, you could buy tickets ahead of time. If you wanted to stay later, you could take the train back (last is 9:20pm). You would either have to take the series of escalators down from the historic center to the train station or a bus from Piazza Gramsci to the station.

There is also a train at 6:18 or 8:18. There are other trains, but these (along with the 9:20) don't require a change.

Thanks kybourbon!

FYI - The escalators (actually a series of about 10 escalators) do not come out near Piazza Gramsci. They are in another part of the historic center (near one of the old gates to the city).

Local buses to/from center/train station pick up street side at Piazza Gramsci (there's electronic signs) and you can buy tickets (validate when you board!)at one of the little stores on the piazza (really a big bus parking lot). Local buses at the train station pick up in the underground parking garage in the mall across from the train station (can be accessed from inside or outside). The escalator can be accessed in the mall also.

May 1st is a major national holiday. Schedules for buses and trains will likely be different that day.

The OP specified that they are looking at the holiday schedule.

I have a question: is it possible or easy to taxi to the train station? I would think so... but I've only been to the bus station in Siena.

Oops, sorry, I missed that.

Yes, I looked at the train schedules for May 1 before I posted. The local city bus may have a reduced schedule. It can be checked on the Siena Mobilita website.

Yes, you can get a taxi at Piazza Gramsci which is the bus hub. There's a large hotel across the street so taxis are always around. The train station isn't very far, but the buses take longer because they make some stops. The escalators (new in the last couple of years) take about 10 minutes. This video show the escalators. There has been more construction at the station in the last couple of years so should connect underground the station to elevators/escalators. You used to have to go outside, but I think the underground is completed.

http://www.youtube.com/watch?v=cNKWTkjj2RQ

Thank you all for chiming in. The advice is greatly appreciated!

we spent 3 weeks operating out of our Tuscany (Certaldo) home base villas in Jun 2012. the Italian train system was easy to understand after our first experience. the trains were reliable, almost always on time, acceptable appearance and much appreciated. we traveled from Certaldo to Florence many times making connections there. the Florence to Certaldo train connection ENDS at Siena where there is a wonderful retail shopping mall and GROCERY store at the rail station. from Siena, the train reverses direction and returns directly toward Florence. I would recommend you take the train when in Italy. we loved it...

The train from Florence to Siena takes longer than the bus. The train station is away from the historic center and the bus drops at the historic center. Bus is the better option for this route, except on Sunday/holidays when it doesn't run as often. The mall/grocery is where the escalator is that I mentioned above.