My philosophy is 30 min of sleep on the plane equals 1 hr in my bed at home.

So, what I do (afternoon flight to HKG):
- is eat, drink, watch a few movies....
- sleep for 8-10 hrs to HKG......
- land...get to the hotel....
- hopefully...the Exec lounge is still open....have a few more drinks...relax....
- go back to the room....relax...11pm....sleep.... and ready for the day.....

If I am going onto say SIN or BKK, then do the above but between HKG-SIN/BKK is eat, drink, watch a movie...then get to the hotel...relax for 30 min...by now it might be pushing 1am....then sleep...ready to go in the am....YMMV....

Late night flight to HKG (see above with caveats):

Just eat and drink watch 1 movie...sleep for 10 hours....breakfast on the plane...get to the hotel, shower, ready to go for the day....stay up until at least 9pm the first night...then sleep.....