Train from Siena to Venice

Italian trains are sometimes not quite as punctual as (let's say) German trains.
The 25 minutes would probably be ok, but it's only another 15 minutes to get the 2nd connection.
I've been on Italian trains that just stopped for 15 or more minutes, right in the middle of nowhere.

Kent is right about punctuality but usually the trains run on time. Florence Santa Maris Novella station is a railhead, so you just walk across the platform for your connection, no stairs or tunnels to contend with. 25 minutes is plenty of time, but the station can be crowded, you need to check the electronic board to see where your connection really is (can be changed). I would plan on the later train and if you have extra time, grab a cappuccino.

Good advice. Grazie.

And make sure you book the train all the way to Venezia Santa Lucia, not Venezia Mestre.

Joan,

There's no way to predict whether there will be any disruptions on the trains that day, but I wouldn't have any hesitation at all in using a train that has a 25 minute connection time. The Italian trains are fairly reliable most of the time and even if there's a short delay, it shouldn't be a problem. Which departure time were you considering?

The trip from Siena to Firenze SMN will likely be via Regionale so DON'T forget to validate your ticket prior to boarding the train on the day of travel, or you'll risk hefty fines.

Were you planning to pre-purchase the ticket from Florence to Venice? Since the trip from Firenze SM Novella to Venezia S. Lucia is via Freccia train with compulsory seat reservations, if you miss that train you could have a problem if you purchased the cheapest Super Economy ticket. DON'T try to use the original ticket on another train, as you'll risk hefty fines which will be collected on the spot.

I'd suggest asking your hotel staff to pre-arrange a Taxi to get from Siena down to the station on your day of travel. That way there will be no "unexpected delays".

Like the others said, you're probably okay with 25 min. to connect, as anything that is going to cause a major delay is probably going to delay you by more than 15 min. I think we connected in Florence from a Venice train over to a Pisa train in maybe 10 min. across the station. The other option is that you wait and buy your ticket to Venice once you arrive in Florence. I know the RS book advises to book in advance to ensure a first-class reservation, though our train was fairly empty -- however the lines at the machines were pretty long, so we were thankful that we purchased in advance and just hopped right on the next one.