Just answering for the "into HKG" part of the question.

Assuming this is a direct flight from Europe (all bets are off if you connect somewhere else, obviously) and that the flight path is similar to that for LHR-HKG, probably left for a closer look at the city.  It appears that the most common approach passes by the city and then loops back.

[![loop approach][1]][1]

However, at least some of the time the approach is more direct, in which case you may be able to see more looking forward out of the right side of the plane.

[![shorter approach][2]][2]


  [1]: https://i.sstatic.net/XZVt7.png
  [2]: https://i.sstatic.net/DdMBK.png