Since everything is closed on Sunday, we decided to take a mini boat trip around Zurich Lake. There is a short-ish trip that just goes in a big circle and takes 1.5 hours. The trip is called "Kleine Rundfahrten" and is part of the Zurich public transportation network. That means, with a zone 10 pass, you only need to purchase either a zone 40 or zone 50 pass (depending on direction) for around SFr 4 per adult.
Just because it is public transit doesn't mean beer, wine and food isn't available. The prices are a bit steep but if a glass of white wine is what you need, it is available. :) They also have sparkling apple juice for the pregnant Americans and kids.
I forgot to mention, you can buy zone 40/50 tickets on the boat if you have a zone 10 pass and there is a ticket window at the departure point, Burkliplatz, for complete tickets.
Details (in German) are available at zsg.ch.