Once in a blue moon, the Schauspielhaus Zürich has plays in english. One for example would be this: http://www.schauspielhaus.ch/spielpl...z/537-arguendo
They also have sometimes plays in german, with english "subtitles". Thats really crappy, because the subtitles are shown left and right of the scene, on small monitors, so unless you're able to look in two places at the same time, you're pretty much screwed.
Not too long ago, Rocky horror picture show was running in Theater 11.
If you're into comedy, you could also try the Zürich Comedy Club: http://www.zcc.ch/
Hope it will help. Should you find anything nice playing, let me know, and my gf and I would join