I did a rail holiday in Switzerland about 10 years ago and, to be honest, would probably not do it again now. My husband had mobility impairments and found it more of a struggle than he'd anticipated. I think now I'm 10 years older with a dodgy hip and creaky knees, I'd have similar difficulties. I'd also agree with what M0nica said above - there's an awful lot of trains up the mountain, trains down to the valley and, as you get more tired, all the mountains and valleys start to look a bit alike!
I'm not advertising and have no connection with the company except as a satisfied customer but, if you like railways, have a look at Inside Track railway holidays. They're a small and specialised company who offer something a bit "different": railway travel, railway and industrial history; scenic locations, excellent hotels and, once you've arrived at the starting point, no hauling of luggage. They offer coach transfers between hotels and stations and between places of interest where trains aren't practical or practicable. Yes, they're not cheap but you do get what you pay for. 🙂
There are holidays in Britain and in mainland Europe and I've been on many, both with my husband and, since his death, either alone or with a woman friend. (Feel free to PM me if there's anything else I can tell you).
railwayholidays.com/