Ok im just back from ZRH I had 6 hours and went sightseeing. I read about the day rooms and they seem very good idea. I would say book into a day room from 7am to 1pm then take the train from the airport to Zurich city it only costs around $10 return and takes 15 mins each way and goes every 30 mins, The train staion is right in Zurich city centre and nice to explore. I would google some Swiss tourism website or Zurich websites for more info. Be back at the airport for around 9pm if your flight is at 11pm just to be sure.

Zurich is worth the visit. Lucerne is only an hour away also so you could do a few hours in each if you wanted. Its up to you.