The folks here on the Forum helped this geographically inept traveller understand the Berner Oberland [I hope I summarized this correctly]:
Interlaken is the valley floor;
Lauterbrunnen is a little ways uphill;
continue further up and there's a "V" split, and Wegen sits at 4100 ft on one side, and Murren is elevated 5,000 ft. on the other side.
The Jungfraujoch is up beyond the Wegen side, and the Schilthorn is above Murren.
There is extended animated discussion here on whether Murren or Wengen is the better area to stay; each is beautiful and charming in its own way.
The total trip to Murren from Pontresina took about 6.5 hours with about eight changes. It was a rather efficient and non-hectic process, thanks to the Swiss and their "maddenly efficient" train systems.
The first 5.5 hours was on the SBB rail lines and involved about five smooth train changes. The SBB lines ended at Interlaken Ost. The next part was totally confusing to me, and I posted a late night-before query here on this Forum: "how do we actually get up to Murren?"
Soon I had received several very easy-to understand responses, assuring me that the Swiss had made the route, and the three changes, which took a total of an hour, quite easy once one was in Interlaken Ost:
1. train from Interlaken Ost to Lauterbrunnen;
2. gondola to Grutschalp
3. "streetcar" one-car train into Murren-
Yes - Success!!!
We chose Murren at which to stay for four nights. [We had previously spent two night here with an RS tour, but had poor weather, so didn't ascend to any peaks. ] Hotel Bellevue, an RS favorite, welcomed us with an RS discount, great email communication, breakfast, and a fair cancelation policy. [Before Covid, did we worry about cancelation policies?] Booking directly with the hotel saved $$$. Our standard room was as described: clean, cozy, small balcony, with view of a mountain, and a very new and somewhat large bathroom. The room itself was European small. I debated about reserving a larger room on the Eiger side of the hotel, maybe even one with a corner balcony. It would have been another sobering 30% more, but now I think we should have splurged. Our plan was to slow down in Murren, and a larger room in which to relax may have been worth it, especially with rain coming. The hotel lobby was large and welcoming, with several overstuffed leather sofas and game tables; a great area in which to read on a rainy day. The hotel also had a large outdoor patio facing the mountains, where they served dinner, drinks, and had patio furniture. On our first two evenings we had magnificent golden sunsets, some of my best pictures of the trip! The Coop store was two Murren blocks away, and the hotel had the only landramat in town. The hostess, Ruth, was wonderful.
I'm a vegetarian, [ I eat chicken], so Swiss dining can be a challenge. The restaurant at the Hotel Jungfrau had Thai chicken skewers [the 12-piece order feeds two] and a great vegetarian pizza. They served us free water with ice cubes! On one night we purchased salads -and wine- from the Coop store for dinner. We took the wine downstairs and sat on the large outdoor patio.
Our initial plan was to spend our first Murren day as a slow-down day, as the day before involved a lot of travel, and we had been on the road for a week. However, inclement weather was coming in two days, so if we wanted to get to a peak, it had to be the next day. We chose the Jungfraujoch.
...to be continued....