High speed rail buy in advance or near to travel date?

You will save some money if you buy the tickets in advance.

Tickets here only [no resellers, no Raileurope]:

https://www.trenitalia.com/tcom-en

https://www.italotreno.it/en [private competitor with lower fares on some routes]

Your day trips may be regional trains, in which case you just buy those tickets after arrival in Italy. I've always done it on the day of travel.

Where are you thinking of going on your day trips? The trip to Siena is best made by bus rather than by train, because of the locations of the bus and train stations.

The only reason to buy tickets in advance is to take advantage of any discount tickets. Each train has a limited number of discount tickets available. Once sold, that is it. However, the discount tickets come with restrictions --- basically no refund, no change. SO --- if --- absolutely certain that you want train A, at 10 am on a Wednesday morning, buy the ticket now and save a few euro. IF uncertain ---don't. The one exception to all of the above is the Regional trains. Price is fixed, never changes, and no seat reservation. Just show and go. No seat --- stand till one is available. Think -- bus on rails. Also very cheap.

Regionale trains tickets NOT purchased online are day-specific, not train specific. It's quite handy, but to prevent re-use it's mandatory to time stamp these tickets before getting on. Forget it and you could be fined.

I purchased mine from Rome to Florence and also Florence to Venice for our trip in April. If you sign up for the Italo newsletter you will get discount codes. We saved 40% on our tickets which was worth it for us.

I don’t like not having everything set in place before I leave. . But that’s just me, and probably not the way most do it, but I buy my tickets in advance. I want to make sure I have a seat the exact time I want to depart.

I think right now it's worth weighing the risk (which is greater than zero) that the trip may not happen as originally scheduled against the savings offered by purchasing tickets in advance. Even pre-pandemic, I wasn't totally confident a trip would happen on schedule until I arrived in Europe. I do like the idea of paying (making these numbers up) 30 euros vs. 65 euros for a train ticket, though.

I always buy my tickets in advance. Paying a little extra for the flexibility to change is wise in the current climate. I have never had an issue with changing my tickets either.

Thanks to all of you for responding. Much appreciation.