Because of what I have read on the forum we will be taking the bus from Florence to Siena. But I was wondering since we are going from Siena to Venice on 5/29 whether we should take the train the whole way (with a change in Florence) or take the bus back to Florence and then take the train to Venice. Thanks for your advice.
I would opt for the train, since there is a high speed train from Florence to Venice.
The advantage of the train is that it takes you inside Florence SMN station where you just have to change tracks to the train to Venice. The bus will leave you outside the station and you will have to make your way inside and locate your track. Also, if you ticket from Siena to Venice, your connection will be protected if the train is late and you can get the next train. You can then buy a discounted, nonrefundable ticket for the Florence-Venice leg. If you use the bus, the tickets are separate, and if the bus is delayed, you would have to buy a new ticket to Venice if you missed your intended train.
Thanks so much Sam and geo! I was thinking the train would be an easier way to go.
The reason people suggest the bus is that it brings you close to the sights in Siena then the train does. So for a day trip to Siena from Florence it is indeed a good option.
However when changing bases, when travelling in other words, I would take the train. And I personally would even take the train for a day trip. Trains have improved on that route recently.