We will have 2 nights/3 days between Tirano and Basel and trying to decide where to stay. Looks like we'll do the regional trains along the Bernina route (thanks to advice on this forum) but not sure where to stop along the way or stay. Could be 2 nights in one place or two night separately. Had been thinking two nights in Chur with a day trip to up high from there, but maybe we can stay someplace(s) high and beautiful? This is mid-May. Thanks!
(Looked through the forum and didn't see this addressed...)
Pontressina is charming!
As a local, I'd stay in Chur.
For a day trip take the train from Chur up to Arosa [https://en.wikipedia.org/wiki/Arosa]. There is a very nice little lake loop walk you can do there or hope on their local post bus service and do a loop around to get a good view of the area and so on.
Another option would be to do a train loop around from Chur to Preda, Klosters and back to Chur. Here is the local train map:
https://www.rhb.ch/de/buendner-gueterbahn/bedienungspunkte/netzuebersicht