I really like the people at Sprachwelten (www.sprachwelten.ch). They have small classes and the staff are very friendly and helpful. It's a very informal atmosphere and I would make my tea in their kitchen before class starts.

And the teachers are also quite good. I've been going for a while now and have had no complaints.

Most schools like Sprachwelten let you have one if not two classes free to gauge for yourself which suits you. Most offer Goethe Institute classes. I dont know if there's a Goethe school in zurich but most schools carry out the Goethe curriculum.

~ Nanda.