In reply to Oliver Wright:
Most people just rush off to the summit and miss one of the most spectacular sights of Kinabalu, dawn chorus. If you have time, spend an extra day/night at the Labang Rata rest house. This will give you time to:
1. Explore the summit plateau, solo a few peaks, etc.
2. On the second night, descend down to Layang-Layang hut which is just above the canopy. Try and get there before dawn. You'll be treated to a sunrise over the canopy and lot and lots of birds!
BTW ok this with your guide first.