I visited Montreux in the summer and while there is nothing more specifically commemorating the group there are a few good places to visit.
The old Mountain Studios is always good even though you can only see the door and it's tucked away at the side of the casino
Lake House is about 10 minutes away from Montreux by tram/bus and can be seen from the boats that sail on the lake
And if you're really obsessed (like me) Freddie had an apartment on the way to Territet in a block called Les Tourelles
A good place to stop by if you're passing is the Bazar Suisse which has loads of Queen souvenirs! ( My family had to drag me out!)
Hope you have a good trip