Best Train Travel for my Destinations

I'm sure there is some logical flow, but Switzerland is so small and so well connected with trains, it almost doesn't matter.

I'd go Zurich, Luzern, Muerren, Kandersteg, Bettmeralp, Zermatt, Bern, Zurich.

The views from the train are prettiest from Luzern to Mürren, so go from Zurich to Luzern. From Luzern take the Luzern-Interlaken Express train to Interlaken Ost. From there, take the train to Lauterbrunnen. From Lauterbrunnen take the cable car up the cliff to Grütschalp where you catch the waiting train to Mürren.

This is helpful, thank you. It looks like from Murren (I plan to spend 5-6 nights) I will go back to Interlaken and then travel via train to Kandersteg and then through Visp onto Zermatt. The train map I found https://cdn-doc.myswissalps.com/docs/default-source/rail-network-maps/swisstravelsystem.pdf?sfvrsn=7788603a_34
shows a dashed line on the way to Kanderstag does this mean this section is through a tunnel. Also if I have limited time, between Kanderstag, Riederalp, Bettmeralp are their any recommendations. Since we will be going to Zermatt I am looking for something a little more off the beaten path, less touristy but still very beautiful to spend 1 or 2 nights.

Thanks for the information so far!

Yes, dotted lines mean tunnels. If you go via Visp between Brig and Spiez you will go through the basis-tunnel. If you want the old line through the high route you need the Lötschberger stopping train which goes between Domodossola and Spiez. Much slower but much more scenic.

You take the "Loetschberger" from Spiez to Kandersteg, which is right before the old Loetschberg tunnel. From there to Zermatt, you continue on the train through the tunnel and down the "ramp" to Brig. Sit on the right hand side for the view. At Brig, the train to Zermatt (or to the Betmeralp cable car), is outside the station in the street, believe it or not.