Kuala Lumpur’s modern new airport (KLIA) luckily provides very acceptable facilities for spotting aircraft.
In the International Terminal, follow signs for the viewing area, which is upstairs past the food court.
The large room overlooks most of the parking areas, and has views extending to both runways. It is surrounded by glass, but is usually acceptable for photography. There are seats and departures/arrivals boards provided.
You can see across to the pier, but not beyond it, which makes it difficult to see anything parked on the maintenance or cargo ramps. These can, however, be seen if you are in the remote pier departure areas.