Must-See Things in Zurich?

Good morning, internet. My wife and I are heading out to a vacation in Zurich in a couple of days. We’re staying with friends there, but what are the Hive-Mind’s recommendations for must-see things to see or do or eat while we’re there? We’re going to have a seven-month-old with us, so things like a night at the opera are not really feasible. We have five days to play with. Tell me what we must do!

I hear the prisons are very nice.

The gnomes.

Abilio can probably answer this a lot better than me, but just walking around is always a pleasure in the older parts of Zürich. Go see where Lenin lived (it’s a pretty neat area)!
Obviously go look at the Zwinglified churches completely without decoration.
Switzerland has a pretty great train system, so start looking at what you can reach in an hour that’s nice in the fall. I sort of want to recommend Säntis, since it’s a way to get the Alp experience without all the hiking, but it’s more than 2 hours out with train and bus. (1.15 with car).
Going to Schaffhausen and seeing the Rheinfall might be nice, or complete anticlimactic if you’ve seen real waterfalls (I personally like it even though I’ve seen the Niagara Falls).
In the summer I’d recommend a visit to Konstanz, but at the moment, it’s mostly foggy :(