We went to Zurich for a short Easter break. For me, the main reason to go there was to photograph airplanes at ZRH. My research indicated that the airport is among the most plane spotter-friendly in Europe. And, boy, wasn't that the truth! The airport has two observation decks. Getting to the Observation Deck B requires a 5CHF ticket and a pass through security. Ironically, observation decks are usually not the best locations for photographing aircraft, but both decks in ZRH are notable exceptions from the rule.
Observation Deck B is so close to the taxiways that you can literally see pilots waving to the visitors. There is a sweeping view of taxiways, and you can capture departures from RWY16. There's a free shuttle bus from Deck B to Deck E that runs every 30 minutes starting at 12:15. The second desk offers a true smorgasbord of photographic opportunities: departures from RWY16 and RWY28 along with taxiing and parked aircraft. It's also worth noting that neither decks have glass panels, meshed fences, or other nonsense whose sole purpose is to make watching and photographing airplanes less enjoyable.
Add to this squeaky clean bathrooms, food and drinks options, info stands featuring airplane trivia, and you have two perfect locations for spotting and photographing airplanes. Heck, Deck E even has loudspeakers tuned to the ATC frequency, so you can listen to communication between the tower and aircraft.
There several other locations around the airport, but I'm not sure whether they are worth the trouble. In a fit of curiosity, I explored the P6 parking house, but it really didn't offer anything outstanding.
By the way, getting to the airport couldn't be easier: it's a 10-minute train ride from Zurich Central Station, and there are plenty of departures to choose from. A one-way ticket costs 7CHF.