Agreed that that's not a good route for Eurail pass use. If you choose the Swiss Transfer Ticket + Half-Fare Card at about $215 per person, then it will act as your ticket to cover you from the Italian border to Lauterbrunnen and out again to the French border at Basel. If you do just the Half-Fare Card at $128, then you have to buy the Swiss portion (with discount) of your Italian travel day online from www.sbb.ch.
The French TGV from Basel (or other city) to Paris, is the most expensive ticket and therefore has largest savings for advance purchase, on sale now for summer travel. (With a 2nd class rail pass, the seat reservation fee on this TGV is $32.) Your Italian routes are shorter and have more trains that can work for you, if you're not ready to commit to dates as far ahead.
You can save a train connection by going to Cinque Terre before Florence.