<<"Thank you so much for the input, Slowpoke. The line connecting Valais and Spiez is an excellent option indeed. This Lötschberg line will take us to Bern. Constrain is this: we live via Geneva ( to Spain). So, Zermatt to Brig to BernBern to Luzerne (Bern–Wolhusen–Lucerne railway line)Luzerne to Geneva.Is there a better way of planning the route... if we plan to cover Bern, and Luzern, and end up In Geneva.">>
Depends on how much time you have. You'll have to work the time table to figure it out.
There is one other very good option. I like it much better.
It gives you a very scenic route through the Brunig Pass. If you want that scenic route...also highly recommended - take what is called the Interlaken Luzern Express. It use to be called part of the Golden Pass line. Once per hour from IO, 1 hour 51 minutes to Luzern.
Zermatt to Visp to Brig to Spiez (via the Lötschberger, not by the new boring Lotschberg Basis Tunnel) to Interlaken Ost.
Then, Interlaken Ost to Luzern...force that scenic route by using Meiringen for "via. " Sarnen or Giswil should also work.
Stop at Luzern.
Then go on to Bern .
The fast route goes through Zofingen and just bypasses Olten. One hour. Newer, faster, straighter main line track. "Neubaustrecke."
The slower route which you mention via Wolhusen takes 1 hour 29 minutes, goes through very scenic Emmental country, and passes through Langnau on the way to Bern. I always go that way unless i am in a hurry. Before the fast track near Olten was installed, that was the normal route between Luzern and Bern.
Finally, Bern to Geneva. Fast, main line trains. Unless you have lots of time, Zürich should be a secondary priority. I love the town, cultural events, museums, things that you find after you spend time there. But it is not such a good tourist destination as the others we have discussed.
If you take that route from Bern to Geneva, you will most likely go through Lausanne.
As you begin to approach Lausanne, soon after you pass Palezieux , and immediately after you come out of the tunnel at Puidoux, sit on the left. Some of the best views in Switzerland are there...the lake and the Alps... then the vineyards.
One of the towns is named Grandvaux...for good reason.
Let me know if that is not clear.
I highly recommend that you consider the routing I have just given. You'll like the views from the windows much better than if you take the somewhat faster routes also available.