Switzerland in January

Hi all! We're heading to Switzerland to celebrate our 30th, and we were lucky enough to book the Glacier Express! We'll be away for 5 days, so we'll fly into Geneva, where we'll visit CERN, and spend the night, then the next day we'll travel to Zermatt for the night, ride the train to St Moritz and then head to Zurich.

We'll be in Zurich for a couple of days before going home, so I would love some suggestions on things we should see or do!

And do you have any tips on the best places for food? We obviously have to go somewhere for fondue and Swiss chocolate!