You could take the train to Thun (20 minutes), which is a pleasant place to walk around (architecture and riverfront cafes to relax) and has a beautiful lake front view of the Alps. From there you could take a bus to Beatenburg, then a gondola to Niederhorn for a great hike with excellent views of the Alps and the lake.
You can also take a boat cruise around Lake Thun or just go part of the way and take the bus back to Thun.
Lauterbrunnen is 90 minutes by train, but it’s an incredibly scenic valley in the Alps with much to see.
Murten (medieval town with standing rampart walls) and Avenches (Roman amphitheater) are 30 minutes to an hour away.
Check the weather each day and head to the destinations that offer good weather; start with your priorities and if they have good weather, then head for those on the first day that offers good weather.
The architecture and historic sites can be appreciated in the rain; it’s hard to enjoy the view of the Matterhorn when it’s hidden behind clouds and rain.
All the best,
Raymond