Is it possible to buy a bus ticket the day of this trip? Just curious if buses sell out quickly and, if so, how far in advance I should purchase? Also, if I do purchase in advance can the ticket be used any day or does it have to be used the day I buy it?
yes you can get ticket on the day. it's not likely to get sold out. you may want to show up a bit early though. I've taken buses on the national day, bus tickets were still available on that day to siena.
Gabriel, Yes, it's possible to buy a ticket for the Bus on the day of travel, but I'd probably buy the day before the trip. My memory is a bit "foggy" on this, but AFAIK the ticket will be valid for a particular time range (ie: a week), but YOU MUST validate prior to boarding the Bus on the day of travel, or face hefty fines. This is similar to the method used with Regionale trains. Hopefully one of the others can confirm the information I've listed. Happy travels!
I bought my ticket about 30 minutes before the bus was to leave. There were plenty of empty seats on the bus. But this was in February so might be different in the summer. I don't remember the schedule but I suspect the bus runs every hour or so to Siena.
Note that there are two types of bus runs. 1) the Corse Rapide is the non-stop run. 2) the other type of run makes a few stops along the way and thus takes a bit longer. You should not have trouble walking up and getting a seat. The buses are quite frequent.
FYI: The buses park across the street from the Florence train station, to the right of the McDonalds and around the block. McDonalds is out the side door.
There is a very large bus area just outside the front and to the left of the main Florerce train station. You can see the McDonalds off to the left at the corner of Via Nazionale. However, these are not the buses that go to Siena. These are local Florence buses. Tour buses do queue up to the right of the McDonalds between Via Nazionale and the next street down. The buses to Siena, San Gimignano, Poggibonsi and other locations depart from the SITA bus station in the opposite direction. It's about 800'-1,000' from the main Florence train station and you can't see it from the main train station. As you step out the front of the station with the tracks to your back, the SITA bus station is to your 90-degree right. You can see the street that you need to go down but you can't see the bus station. Here's a Google map link to show you the SITA bus station. The front of the main Florence train station is the shorter building in the middle of the picture. This SITA station is also shown clearly in the Rick Steves Florence book. http://gyazo.com/b3759691858f7d086b34c2381bb53961
Thank you everyone for your input. I already have the RS guidebook and have read it thoroughly. I'll be staying near the bus station so I'm sure I'll have no problem finding it. Just wanted to be sure I can buy a ticket the day before and use it (validate it) the following day.