Jan 19, 2017 - 1:46 PM
in reply to Swissty
Lucerne is a really nice town on a lake with endless options for days trips. St. Moritz is also en route and amidst wonderful mountains and also on a (small) lake.
Scenic trains all cover routes that can also be done using regional trains. It's up to you what suits your plans best, and whether you mind changing trains a few more times, which is often required when taking the regional trains (not a big deal though). Our scenic train pages explain all about it.
If you're in Switzerland for multiple days it's unlikely you would not save money with a rail pass. Rail passes are actually public transport passes, so boat trips and cableway trips will be discounted or free as well. The Swiss Travel Pass mentioned by Lucas even includes museums. Once you have an itinerary you can have a look at the options, include the "how to choose" page Lucas linked to.