Aug 25, 2015 - 7:50 AM
Welcome to MySwissAlps, ronnieroop!
With a 3 day Swiss Travel Pass, you should limit your trips on the first or last day of your stay. So I suggest you spend either September 9 exploring Zurich, or September 12 exploring Geneva. In between, you can get to Zermatt using this scenic route: first, head for Lucerne and then for Spiez via Meiringen. This is part of the Golden Pass route. Then, board the regional Lötschberg train via Goppenstein towards Brig/Visp and head for Zermatt. The timetable will provide all details and it allows you to enter 'via' stations to search for these exact routes. Highlights in the Zermatt area are the Gornergrat and Klein Matterhorn. After your visit to Zermatt, you can continue towards Geneva, maybe with a stop-over in Montreux.
Of course there are many more alternatives, but I think this option matches your wishes.