Regional Train from Siena to Florence

1. sometimes it's crowded and sometimes it isn't, for sure most commuters and students take Regional trains and AT buses before 9:30 AM.
2. Regional trains are often 10 minutes late. Is Siena an intermediate station or the departure one? Will it stop in many stations before calling at Florence? A train that begins its run from Siena won't depart late but may be late in Florence because of the number of intermediate stations.
3. That would depend on the train type they will use on that line on that day: https://youtu.be/fArjBI7hbXs?si=U2gL9_0rsTLJi9wx or https://youtu.be/qDvlz93PoH0?si=E-Hbs78nIovnpMFD or https://youtu.be/qva5Vo_eQrI?si=Rr6L0Jnhsyw9oMwp The last video shows the newest typr Regional train that serves that line.
4. It's cheaper. Buying tickets on the day of travel you'll pay Trenitalia's Base fare and Italotreno's Flex. These are the top fares. Otoh, If you wait to purchase there is no reason to choose in advance between Trenitalia and Italotreno.

You might consider taking the bus from Florence to Siena.
It is faster and drops you up in town as opposed to the train- station is at bottom of the hill.

marco.tullio.falcione - Thanks for the links. Siena will be the departure station.
ChristineH - We'll be going from Siena to Florence, not Florence to Siena.

From the videos, it doesn't look like the trains have much room for carry-ons. Would we be better off taking the bus as ChristineH suggested?

We'll be returning our rental car at Hertz in Siena, so if we took the bus we'd have to go back up to the bus station. If I've read correctly, the train station is closer to Hertz than the bus station.

We made the decision to return the car in Siena because that seemed easier than dropping it off at Hertz at the airport. Should I reconsider that? What would be the least hassle given we have luggage: 1) Drive to Florence and return the car there; 2) drop the car in Siena and take the train to Florence; or 3) drop the car in Siena and take the bus to Florence?

When you pack heavy it's easier to take the bus because you stow your bags before getting on.

We'll be going from Siena to Florence, not Florence to Siena.

oops.
In this case and since you have the car- I think the simplest plan is to return in Siena and train to Florence. Are you moving on that same day to Bologna? If so you are right where you need to be to catch that train.

Dropping at the airport is out of the way and would require a shuttle/tram or taxi to get back to Florence station or center.
The other option is drop at Hertz near Florence station- there are directions here on the forum on how to do that without getting ZTL fines- but honestly- dropping in Siena would just be simpler.

Be sure to check the open hours at Hertz they usually close mid day 12-4ish, close at noon on Saturday and are closed on Sun.

If you are sure of your dates/time I would buy the fast train ticket in advance- Trenitalia or Italo- both have easy to use apps.

The trains that depart Siena at 18 past the hour originate in Siena. so arrive early and you will be the first to board the train, find seats and claim luggage space.

If you are actually traveling to Bologna, why not just buy a single ticket from Siena to Bologna? Then your connection in Florence is protected.

Ah, that does make sense to buy one ticket. I see that there's ticket option for the Trenitalia (regional) and Frecciarossa (fast train) combo. That'll work!

Thanks to all for your suggestions. So helpful!

You could also return the car at Hertz in Florence, which is next to the SMN station.

If you return the car in Siena before going to Florence the train makes more sense than the bus, as Hertz in Siena is closer to the station thank to the bus terminal (however Hertz is not really walking distance from the Siena station).

Is it easy to get a taxi from Hertz in Siena? Are taxis waiting outside or do I need to arrange a taxi ahead of time?

Just ask the guy at the counter to call a cab for you.

In this case I would book a Siena to Bologna ticket with Italo. They do offer combinations of local + high speed trains, and booking in advance saves you money. You can do the same in Trenitalia.

Generally speaking when travelling by train it is always advisable to have the whole trip on one booking.