Zurich is a big city and requires not only a full day, but also a full tank of energy. It's a lovely city, although having been to Lake Konstanz in Germany, Brian and I both like that better.
But, if you're in Zurich, there's one thing you need to do. Stop at the Confiserie Sprüngli for some Luxembourgers, a delish confection that melts in your mouth. We go there every time we're in Zurich.