Which rail pass for 5 days Zurich to Florence?

My husband and I will be travelling to Switzerland early July. We will be flying in to Zurich and staying in Switzerland for 5 days before moving to Florence. Below is our itinerary, any suggestions as to which rail pass we should get in order to be cost efficient? Thank you!

Day 1: Zurich

Day 2: Zurich to Lucerne

Day 3: Lucerne

Day 4: Lucerne to Interlaken

Day 5: Interlaken to Zermatt

Hi Vivian, and welcome to MySwissAlps!

The best choice also depends on your day trips, like what you will be doing while in Zurich, Lucerne, Interlaken and Zermatt. At first glance a 4-day Swiss Travel Pass (day 2 to 5) may work, as there are other options (like a ZürichCARD) for day 1 in Zurich. Also you would need a ticket to Italy.

The above links provide more information. You can also take a look at these instructions if you're unsure about which pass to pick.