For a points redemption the CY Sha Tin wins hands down given that its cash rate can creep up to ~HK$1800 when it's full of tour groups and the cash rate at CY HK, Le Meridien and even the Marriott Ocean Park can be lower (I've seen this some weekends). If the OP is looking at HK then Ovolo can be had for ~HK$800 a night. Book direct (still getting Bonvoy nights and points) and you get their breakfast and happy hour free flow drinks in the evening.

But I'd agree that KL is probably best for Asian mattress runs especially if you travel there using Air Asia and get a dirt cheap flight - something that's lacking if you fly to HKG. Could also try the Four Points Sandakan which is a very nice hotel quite out of the way and cheap.