Lauterbrunnen and the valley are spectacular, and from there it is convenient to travel to either side of the valley for day hikes higher in the Alps. The rail system and cable cars make it really easy to get to some great hikes on short notice. On good weather days, it is worth staying up there to enjoy the views and walk a bit.
The train from Lauterbrunnen to Wengen is also very scenic, and Wengen is fun to explore as well or take a cable car to Mannlichen.
Even if it’s cloudy with some rain, you can have some beautiful views in the Lauterbrunnen – Wengen – Murren area, but it’s also good to be there for at least one sunny blue sky day to enjoy the grandeur of the Alps.
On cloudy rainy days, there are several options. Here’s a link to a discussion of these:
https://community.ricksteves.com/travel-forum/switzerland/rainy-day-cloudy-day-things-to-do-in-jungfrau-region
If you book the Matterhorn day, and the weather is bad, Bern makes a good day trip, and it has covered arcade walkways.
If you want to explore other areas, then Lucerne is a good choice (as others have noted).
You could also do a day trip to Bern: interesting fountains and clock towers, covered arcades, lots of people watching and some good restaurants. It’s a short trip from there to Interlaken or Zurich.
The smaller city of Thun is across the lake from Interlaken and has an interesting city center along the river with nice cafes/restaurants as well and a pleasant walk along the lake. It has two castles as well.
For a different region: Murten and Avenches are a convenient day trip from Zurich/Interlaken or you could stay one night there. There is more French spoken here; Murten has a fascinating wall around the old city which you can walk in a few hours. There are several nice restaurants and plenty of people watching. The nearby lake attracts lots of visitors in the summer, not sure about how many folks will be there in April. Avenches has Roman ruins. You could also visit Neuchatel while in the region.
Another option is Lausanne/Montruex, also in the French speaking part; it’s more wine country, with a beautiful lake and walks along the shore; there is a nearby chocolate tour and Gruyere. Lausanne has a nice food market; I got some Gruyere cheese there.
You might find that a 3 or 4 day rail pass is worth it for the days not covered by your official tour; just check a few fares based on your plans, then compare to the rail pass price.
Download the phone app to use when you’re there; the system is very efficient and easy to use.
Mobile Phone App
https://www.sbb.ch/en/timetable/mobile-apps/sbb-mobile.html
All the best,
Raymond
