Checked out the Amica fares for discounts Rome/Florence/Venice.
Is there a big difference between first and second class on the trains?
If I purchase my first tickets here, do I get a confirmation number?
Are Amica fares available at the Termini from the vending machines or only where there are manned ticket sales booths. The reason I ask is that we won't get to the train station until after 7pm on a Sunday night, so I want to buy our tickets for Tuesday's trip to Florence ahead of time. Should I just buy them online today?

1st vs 2nd class - there is always a difference - 25% less seats in same space in first class - you can ask for i believe the aisle and window seats (1st cl has 3 seats in a row - so-called isolated seats of single seat, then aisle then two side by side seats

and solo seats can face each other and may have a table inbetween them - two by twos may face each other as well with table

many seats may only face one way and only fold-down tables - more room for luggage in first class and could be empty seats to spread out in

2nd class is two rows of two seats - but that said on Eurostar Italia trains the difference between classes is less than on some trains - quite comfy but no isolated seats (on aisle and window) like i like.

Ticket windows at Termini will be open far after 7pm on Sundays - not sure if can do on machines so will leave to others like TimS and Ira (keep topping until they're on forum)

You can also buy them at Rome Airport train station if arriving there - or any station in Italy, need not be in Rome

Should you buy online? If sure of your time yes - that said, unless you have successfully figured out the site, good luck! And Amica fares are sold few days before the train IF any remain so book now to save money and time once there IMO if you can do it.

awesome, thanks. I will try to buy online and see what happens!