Two weeks in Switzerland

Buy Rick Steves CH guidebook: https://store.ricksteves.com/shop/p/switzerland-guidebook. An updated book is scheduled in Jul’25.
You definitely want to visit the Lauterbrunnen Valley, Zermatt and Luzern.

Is the entire trip 14-16 days including Paris, Germany and Vienna or do you have 14-16 days just in Switzerland + those additional time for the other places?

If you have 14-16 nights in Switzerland, I would suggest:
Lake Geneva (I recommend Vevey) for 3-4 nights
Zermatt for 3 nights
Luzerne for 3-4 nights
Murren, Wengen or Lauterbrunnen for 4-6 nights

I will address your train travel first. My view is that multi-country Eurail passes are not a good plan any more. The fast trains in France and maybe Germany need seat reservations which must be purchased separately and add to the cost. And they are limited, so people have reported being unable to get them for the trains they wanted.

If your travel before Switzerland is simply Paris to Colmar to Freiburg in Germany, you can often get a discounted price by buying those individual tickets in advance. I have found the French site SNCF quirky and difficult, so I use Trainline.com instead; they will pass on whatever discounts are available. For your trip from Freiburg into Switzerland, you can get a good discount on the cross border ticket by buying 2-3 months in advance from the Swiss rail company, SBB. If your travel that day ends in Bern (a city we like very much), the ticket from Freiburg (Breisgau) which regularly costs 68 CHF is reduced to 21 CHF for a non-flexible ticket, or 28 CHF for a semi-flexible one. Make sure you use Freiburg im Breisgau; otherwise you might be getting a ticket from Fribourg in Switzerland (which in German is spelled Freiburg).

With 2 weeks in Switzerland, my choice has always been the simple 15-day Swiss Travel Pass, which covers all travel by train, bus, and boat between Swiss cities and villages, including most villages perched high up on mountainsides like the ever-popular Mürren and Wengen. With this pass, you don’t need seat reservations; you just hop on the train (or boat) and sit wherever you like (in the class of travel matching your pass, First or Second). This gives you complete freedom to choose your daytrips at the last minute, according to whim and weather. The pass also gives you 50% off most of the high mountain (recreational) cablecars and cogwheel trains.

https://www.sbb.ch/en/tickets-offers/tickets/guests-abroad/swiss-travel-pass.html

This map of the Swiss rail system, with scenic trains highlighted, shows the routes fully covered by the Swiss Travel Pass (solid lines in red, black, yellow and blue) and 50 % coverage (dotted lines, with exceptions noted by a circled number (1).

https://www.travelswitzerland.com/en/download/swiss-travel-system-map-en-2023/?wpdmdl=14294&masterkey=63a023c8da36c

Before suggesting specific towns or villages, it would be helpful to know more about your interests—-mountains, lakes or picturesque towns and villages; cultural events; food and wine; French- German- or Italian-speaking areas (or even Romansch in the eastern Canton of Graubunden). I will note that Sep[tember is a good time to see harvest festivals, “cheese-sharing”, and parades with decorated cows descending from the high pastures.

Wandrweg: Our plan is to spend 14-16 days in Switzerland.

Caroll: Thanks for helping break up the days to spent in each location.

Lola: Really appreciate your explanation regarding the train system and I plan to follow your suggestion and will buy the 15-day Swiss pass. I realize that two weeks is not enough to see everything and that is why we are planning to stay in only four towns/villages (3-5 nights) to get a feel for the area, instead of just running around taking selfies.
Any suggestions regarding must see sites, cultural events and places to stay would be appreciated.
Thanks.

Having just done an almost three week trip, I agree pretty much with Carroll's breakdown.

We didn't stay in Lucerne or Zurich as we had done that on a previous trip.

This time we stayed in St. Moritz for a couple of nights, then three in Zermatt. We loved, loved Zermatt but I defintely think you need three nights if, like us, seeing the Matterhorn is a priority. We had one wonderful day when it was completely visible, but the other day and a half it was obscured by cloud.

We had five nights on Lake Geneva, although we chose Montreux and were pleased that we did. We stayed at the Hotel Suisse Majestic in a Lake View Junior Suite. The hotel was perfect, as the station was literally over the road on the other side so getting around for sightseeing was so simple. Our views and the peace from the lakeside were wonderful too.

The best part of our trip was the seven nights in Wengen. We stayed at the Maya Caprice, again in a junior suite with a sensational view. We were only minutes from the station once again, and walkable to the shops, restaurants and cable cars.

There is nothing I would do differently, it all worked out perfectly.

All, thank you for your advise and recommendations.