Updated itinerary questions

I would scale Berner Oberland back to 5 nights, allowing for ...

Either,
•Luzern for 3 nights
•St Moritz for 2 nights
- allowing a day for the Bernina Express
•Berner Oberland for 5 nights
•Montreux/Lausanne for 4 nights
•Bern for 2 nights

Or,
•Luzern for 3 nights
•Berner Oberland for 5 nights
•Zermatt for 2 nights
- allowing a day for the Gornergrat
•Montreux/Lausanne for 4 nights
•Bern for 2 nights

Note that you have very early trains directly from Bern to Zurich Airport. Perhaps spend a day in Zurich from Luzern at the front end of your trip.

Vonnie,

Allow me to back up a bit and talk about the larger question, then down to specifics. When asking for input, the more you info you can give about your preferences, the better. For example, I have friends that LOVE riding on Swiss trains, and could do so all day. I, on the other hand, would much rather hike (on easy paths) through similar scenery so I can enjoy it longer and take pictures along the way.
I do see that you did give some hints in a previous note: "...most interested in natural beauty, easy to moderate hiking, castles, quaint towns and countryside. We saw Zermatt on our last trip on a clear day, so won't revisit it this time."

Using that info, here's my suggestions.

Most travelers advise staying in a location more than a day or two, or you spend too much time on the road, plus packing and unpacking. So, based on that, I would advise 3 locations, Lucerne, Montreux, and Berner Oberland. I'll also admit a bias toward the Berner Oberland. Other places that you mention like Disentis or Lavaux are nice, but BO is fantastic. I've brought many folks to the BO region and they all have been wowed. I've been there a dozen times and always for a week or more, and part of the reason is that even if you have 3 days of rain, or fog, or overcast, you still have several other days as backup. And, if all 7 or 10 days are sunny, there's still enough to keep you busy all the time. (I have 10 trails described in previous posts, just click on my name.)
So I'd take take 2 days out of Montreux, and skip Bern, and maybe add a day to Luzern, to give you a week in BO. I recommend staying in Lauterbrunnen, Murren, or Grindelwald.
I'd recommend the Berner Oberland Pass that will cover all trains between Lucerne and Lauterbrunnen and most of the way to Montreux. Plus you get other freebies in there such as free boat rides on Thunsee or Brienzersee. It would also cover a day trip from Lauterbrunnen to the castle in Thun.
I see you live in Grand Rapids, as do I, so feel free to click on my name and send me a private email and I could share some pics with you. I'm a Calvin College prof.
Hope this helps,
Allen

Thank you, David and Shoe. I am pondering each of the three plans. From them I have learned to reduce the number of changes in accommodation, and, instead, seeing places like Thun as a day trip. I hadn’t thought to go straight to St. Moritz from Luzern and do the Bernina Express back and forth as a day trip instead of the RS Best Two Week Trip plan of going to Lugano and bussing through part of Italy to connect to the Bernina Express. Your plan would also allow us to take the Glacier Express route to Montreux. I do want more than three days in the Berner Oberland. Shoe, I will PM you. Thank you again for your suggestions.

1..Arrive Zurich. Train to Luzern (3 nights)
2..Day trip to Pilatus
3..Day trip to Rigi or Titlis
4..Train to St Moritz (2 nights)
5..Day trip on the Bernina Express
6..Glacier Express to Brig, then train to Interlaken & Lauterbrunnen (5 nights)
7..Day trip to Murren
8..Day trip to Jungfrau
9..Day trip to Thun
10..Day trip to Grindelwald
11..Golden Pass Line to Montreux (4 nights)
12..Day trip to Chillon & Geneva
13..Chocolate train to Gruyere
14..Day trip to Lavaux & St. Saphoris
15..Train to Bern (2 nights)
16..Bern
17..Depart Zurich

Thank you, David! How very thoughtful.

It’s great you have a considerable amount of time allowing you to explore so many corners of Switzerland. Enjoy.