I was wondering if it was worth getting the Italy rail pass. I've been to Italy twice-first time I had the Italy pass (on a school trip) and the second I had the Eurail pass. I can't tell from the web-site if I can use the Italy pass on the Eurostar or the faster trains. On the first trip we got on the Eurostar without making reservations and ended up sitting on the floor from Florence to Venice (college professor's mistake). I know better this time, but I want to be able to travel on the faster trains. I remember the Italy trains taking a lot longer. We have a toddler so the quicker we can get from a to b the better. By the way, the itinerary is land in Rome to Florence (same day), day trip to Cinque Terre, Florence to Venice, and Venice to Rome. So we'll need at least 4 train days. We are obviously looking for the best price with the most convenient travel. Any advice would be greatly appreciated.
Point-to-point tickets in Italy are relatively inexpensive so a railpass for Italy alone is rarely cost effective. That will be even more true when you add on the cost of reservations for trains that require them. While most reservations are 3-4 euros, they are 15-20 euros for the fast EuroStar Italia trains.
Amica fares (20% discount) are sold for many routes. If any of the allotted seats are still available, you can buy Amica fare tickets up to midnight of the day before departure. You won't be able to get Amica fares for your first day Rome-Florence ride, but you should be able to get them for your other routes (if those routes offer them) if you buy tickets a few days ahead of time.
Go to the Trenitalia site for timetables and fares. For trains that require them, reservations are included in the price of the ticket.