Fast 35mm equivalent and a gorilla pod should cover you for pretty much everything in HK
I'd go with a good quality 28mm prime - nice and wide yet not heavy & bulky for packing/carrying.
Wow, talk about post no information expect lots back?!
It would help, as a minimum, if you actually mentioned what kit you have!!
Take the Kowloon - Hong Kong Island Star Ferry across the harbour and then a trip on the tram up to the top of The Peak. Late afternoon, towards dusk is good.
Take the cable car the Big Buddah and then the bus down to Tai O.
The Night Market is good fun, 'You want copy watchy?', and has plenty of photo opportunities, though hang onto your kit!
I have heard that you also have to hang on to your plastic as well....