Have you bought the Zurich “Ferienpass” for your kids yet? For CHF 25, your child gets free entry to all badis, free entrance to 45 museums and the zoo, discounts on all sorts of activities like ropes courses and go carting, and free public transportation for the whole summer break. This is great for any kid over 6, but especially for tweens/teens that want some freedom to roam with their friends.
Get info about the ZVV Ferienpass.
And here are links to my posts about some of the activities included in the Ferienpass.