In order to do a circle trip on the train combining the Glacier, Bernina, the Gotthard Scenic train trips, a 3 hr. bus ride from Tirano to LUGANO is needed. I hate buses and am also concerned about Covid in the tight quarters of a bus. Has anyone ridden on this bus and did you enjoy the scenery along the way? Right now I'm not going to Locarno because I resist the thought of a bus ride for 3 hrs. and am using those 2 days to explore Stein am Rhein & Appenzell instead. Is Locarno worth it for only 1.5 days then the bus trip or maybe I'll just stick with the other plan. Any advice or experience is appreciated. Or perhaps do LUGANO instead of Montreux?
Another way to go from Tirano to Lugano is by train. Take the Italian regionale from Tirano to Monza and there transfer to a regionale to Lugano. Takes 3 hours and 50 minutes. At Lugano you can catch the Gothard Panorama Express to Luzern. Then you can take the Golden Pass train to Montreux and you will have done the Big Four.
The cost for the Italian train portion is only 14 EUR. Once you cross the border into Switzerland, your Swiss Travel Pass kicks in for the rest of the journey. Don't forget to validate your ticket in the trackside stamping machine when you board in Tirano if you buy a ticket at the station. And do not board the Eurocity train at Monza as your ticket is not valid on it, only the regionale.
Susan, if you're transferring thru Heathrow you can't go into Italy without quarantine. If you look at my posting history, you'll see where OP's have suggested to get off on the last Switzerland stop, and the returning train will be back in 17 minutes. For our trip, I don't mind doing the Bernina Express route once and then double-backing, as the scenery should be so spectacular. Safe travels!
I'm not sure there's a bus from Tirano to Locarno (although there very well could be). The usual bus route travels to Lugano, along Lago di Como for part of the trip, and as I recall it's seasonal. The bus stops for a "bathroom break" partway along the trip. I haven't checked the schedules on that route lately, so not sure how often it runs.
IMO, 1.5 days is not long enough to see much of anything in Appenzell. Travel time to get there is probably going to be at least half a day (each way).