We are planning a 2-3 week visit to areas mentioned above in spring 2020. We are wondering if it would be worthwhile to obtain an Italian telepass? It’s understood that this will entail a lot of driving and would like any advice that would be helpful in traveling the autostrada. We would like to cross the border going into Switzerland and would appreciate any information regarding boarder crossings between Italy and Switzerland. Thank you!
Look at your proposed route and see if trains are more feasible for some legs. It is really nice to sit back and watch the scenery rather than the road stripes.
You’ll probably want to make it late spring for the Dolomites. There is still snow on the ground - and sometimes new accumulation — well into May. Also, the lifts don’t open until late May into mid-June depending on elevation.
You will need a vignette for driving in Switzerland.
I don't believe you will be able to buy a Telepass. This document (in Italian) is a guide for foreigners driving in Italy, and it explicitly says "Foreigners cannot use the lanes marked with the “Telepass” signage since the toll passes are reserved for residents in Italy"
(original: "Gli stranieri non possono utilizzare le corsie contraddistinte dalla segnaletica “Telepass” poiché l’addebito degli importi per il pedaggio è riservato ai residenti in Italia")
With your proposed itinerary, you won't be on the autostrada much, and the costs aren't exorbitant, so I would just plan your desired route and pay as you go. But yes, don't forget the vignette for Switzerland, that is mandatory.