Info on Singapore's Changi Airport?

[Robbie J]

I'm not sure if this thread belongs here in the Spotting And Movements page or in the Trip Reports page, but I'm seeking info on Changi Airport in Singapore.

I will soon be having a 12-hour layover wait for a flight out of Changi and I'd appreciate comments from those who have visited or photographed it.

Is there an observation deck for photography and spotting? (I'd prefer outdoor shots of aircraft movements, not interior shots of the terminal itself.)

Are there any good/best angles or vantage points to snap images from, preferably not too far from the airport itself? (Think, walking distance.)

I've heard the place is massive, and I'll be stuck there from just before midday until just after midnight for my flight, so I have a decent amount of time to do some exploring.

Comments welcome. Thanks.