Why Zurich? Put that night toward Luzern.
One night "near the Matterhorn" and one night "near Mt. Blanc" means a lot of travel for very weather-dependent locations. If you go all that way and it's cloudy or rainy, you've spent a lot of time and money for not much. Instead, just stay 4 nights in Mürren (that's what I did). Remember that 4 nights gives you 3 full days, which is a good amount of time (you won't run out of things to do), as well as a hedge against bad weather. One of my days was cloudy; I'm very glad it wasn't my only day there.
My 10 night trip in September 2014 was: Land in Zurich and go immediately to Luzern. Three nights in Luzern; much of one day was spent taking the boat and train to Mt. Rigi and back. Four nights in Mürren, where I did Allmendhubel, the Schilthorn, the Jungfraujoch, a half-day in Interlaken, a walk on the valley floor including seeing the Trummelbach Falls, and various walks around Mürren and Gimmelwald. Three nights in Lausanne, with trips to Montreux, Chateau de Chillon, and Audrey Hepburn's grave in Tolochenaz. My last morning, I went right from Lausanne to Geneva airport.
This was a great trip, and a slightly modified version (since you fly in and out of Geneva) is what I'd recommend for you.
EDIT: cross posting with Chris F - you'll see we had many of the same ideas!