If you’re staying at Hong Kong for some spotting, probably the best airport hotel at Chep Lap Kok is the Regal Hotel. This has many rooms with views over the action at the airport.
Clive Hindmarsh recently posted some pictures taken from his room (8066) there www.flickr.com/photos/superspotter
He reports you need to be in the South Wing of the hotel, in even-numbered rooms of floors 7, 8 or 9.
Although the hotel only overlooks one side of the airport, it tends to be the side favoured for runway operations so you should catch most movements.