Generally, there is a simple rule to determine the flying place for the day.
If the wind is easterly and you are big glider fan and want to have good landing site to minimize damage - go to Ma On Shan
http://www.rcsail.com/MaOnShan.htm
If the wind is easterly and you don't want to be alone on the slope - go to Clearwater Bay or Fei Ngo Shan Peak (east face)
http://www.rcsail.com/clearwater.htm
http://www.rcsail.com/fns_a_photos.htm
Generally, Clearwater Bay is more suitable for beginners without a car and Fei Ngo Shan is for more experience pilots and also with a car.
If the wind is northerly, you can go to Clearwater Bay north face
http://www.rcsail.com/cwbN_photos.htm
or Fei Ngo Shan north face
http://www.rcsail.com/fns_d_photos.htm
Same car rule applied.
During the summer, if the wind is southerly or southerwestly, go to Fei Ngo Shan southwest face or south face
http://www.rcsail.com/fns_b_photos.htm
http://www.rcsail.com/fns_c_photos.htm
If there is no wind or very light wind and plenty of sunshine, go to Fei Ngo Shan southwest face, you can fly thermal gliders at noon there.
If you are the one who wants to fly queitly and alone, go to remote places like Ko Lau Wan or Pak Lap Wan
http://www.rcsail.com/OtherSites.htm
Finally, if there is heavy rain, stay home and play FMS.