Need advice as to which trains to take for fastest route from Montreux to Pontresina. Will overnight in Pontresina then take Bernina express to Tirano. Any help greatly appreciated as I have never traveled on trains in Europe.
The SBB (national railroad company of Switzerland) site will show you all your options:
https://www.sbb.ch/en
Search from Montreux to Pontresina and you see all options depending on the the time you want to travel.
The fastest is 6 hours and 3 minutes.
In Pontresina we liked our stay at Hotel Collina.
Usually, the fastest is way is through Zurich. Slower, but more scenic is through the mountains, via Brig, Andermatt, Chur. This route will take 2 hours longer than the fast way through Zurich. Some of these itineraries can use the Glacier Express. Upside is fewer train changes, downside is requires seat reservation fees. Regular trains cover the route in the same or less time, but will require train changes along the way.