Hello Bitsy
Welcome to MySwissAlps.
Thank you for sharing your travel plans with us. I infer from what you are saying that you are going to be able to spend almost the whole of September (from about the 5th onwards) in beautiful Switzerland.
Is this [itinerary] the best for scenic trains and connections?
Please get out a map of Switzerland and keep it in front of you.
Find all the places you have expressly listed in your Itinerary.
Then find St Moritz and Klosters, two places you must surely have heard of, which are situated in the south-east of the country in the canton of GRAUBUNDEN. Also find the city of CHUR, the capital of Graubunden canton, which is only 75 minutes from Zurich by fast train heading south-east out of Zurich.
I have been visiting Switzerland for over 50 years, travelling around using a SWISS TRAVEL PASS (https://www.myswissalps.com/travel-ticket/swiss-travel-pass/). If asked what are the most scenic public transport routes in Switzerland I would always include.
The narrow gauge Bernina railway from St Moritz to Tirano via the Bernina Pass.
The narrow gauge Albula railway from Chur to St Moritz via Filisur. (The curved viaduct you see in many Swiss posters is just north of Filisur).
The narrow gauge railway which runs from Chur to Andermatt via Disentis. (A change is usually required at Disentis.)
The 811 bus route from Zernez (near St Moritz) over the Ofen Pass to Mals/Malles.
The main railway line from Zurich to Chur.
All these routes are either wholly or partly in Graubunden canton.
The possibility of snow.
I think you are worried about snow covering hiking trails. It does make sense to start at your highest resorts, and then (as it were) work ‘downwards’.
Of the resorts you list Zermatt is the highest, and Lucerne. Montreux and Zurich are the lowest.
So if you stick to your original list of resorts, it would make sense to start in Zermatt and work round in the ‘opposite direction’ finishing at Lucerne.
If you decide you want to add in Graubunden canton, put that at the very beginning. St Moritz is at 1,775 metres above sea level, Zermatt is at 1,605.
St Moritz to Zermatt
I suspect you may be thinking, ‘St Moritz is going to be expensive for accommodation’. And then ‘To go from St Moritz to Zermatt I will have to spend a lot of money on the luxury Glacier Express’.
For accommodation in the St Moritz area, (the ‘Upper Engadine’) look at the villages of Samedan, Pontresina and Celerina.
To get from St Moritz (or anywhere in Graubunden) to Zermatt you will want to travel the highly scenic route via Disentis and Andermatt. The Glacier Express (https://www.myswissalps.com/activity/glacier-express/) runs that way, but there are also regular hourly ‘regional’ trains timed to connect with each other.
Swiss Travel Pass
Whether or not you adopt my Graubunden suggestion you are going to be doing a lot of travelling on Switzerland’s superb public transport system. You will probably need to invest in two consecutive 15-day Swiss Travel Passes. The STP is valid on all Swiss PUBLIC TRANSPORT (buses, boats, trams/streetcars etc.) except lines which simply ‘go up mountains’ rather than serving inhabited villages.
All the routes mentioned in this reply are free with the STP. On many lines which simply ‘go up mountains’ the STP gives a discount.
I have given you a lot to think about.
Kind regards
Roger