I now you said you didn't want to do daytrips, but if you do change your mind, Lausanne is less than a half hour away by frequent trains. They have two very worthwhile attractions - the Museum of Outsider Art (Collection de l'art brut) and the Olympic Museum. If either of these interest you, they're well worth the trip.
The most memorable thing I did in that area was see Audrey Hepburn's grave (in Tolochenaz, west of Lausanne), but I realize that's a very specialized interest. There are actually lots of famous people buried in the area - looking online, I found Richard Burton, David Niven, Vladimir Nabokov, Charlie Chaplin, Graham Greene, James Mason, Coco Chanel, and Peter Ustinov. Well, tourists go to Père Lachaise Cemetery in Paris - why not cemeteries in Switzerland?
In the realm of things you're more likely to do, I enjoyed strolling the Montreux waterfront - it's a nice place to just hang out.