I think I have finally figured this one out ! Patrick was absolutely right about the 3country 10day Select Pass. That makes the most sense.

For those who are interested in what we decided to do, here is our plan.

3country, 10day Selectpass Saver - $480

*Day 01-> Vienna-Salzburg
*Day 02-> Salzburg-Innsbruck
*Day 03-> Innsbruck-Bludenz-Innsbruck
*Day 04-> Innsbruck-Lucerne
*Day 05-> Interlaken-Montreux-Interlaken
*Day 06-> Interlaken-Zermatt
*Day 07-> Zermatt-Venice
*Day 08-> Venice-Florence
*Day 09-> Florence-Sorrento
*Day 10-> Sorrento-Rome

The following trips will be point-point tickets.

*Salzburg-Hallstatt-Salzburg
*Lucerne-Interlaken
*Interlaken-Thun-Interlaken
*Interlaken-Jungfrau-Interlaken
*Florence-Pisa-Florence

We are still debating whether to rent a car in Austria or not, if we do, the plan above may change slightly.

Any comments on this plan !? Thanks a ton to all.