Eight hour layover in Hong Kong, time for a look around?
I agree - I go to HKG a fair bit and you have more than enough time to get the MTR express into Central.
The Star Ferry to TST would be a must for me and then see the light show at 20:00 daily - either from Avenue of the Stars or from Felix in the Peninsula. Aqua at 1 Peking Road has a good view too.
You should aim to leave Central on the MTR back to the airport around 22:00 for a 23:30 departure - that's plenty of time as Chep Lap Kok airport is pretty efficient...
FD.