This is a few must do activities. It will depend on the amount of free time you have. Please do not forget to browse the Discover Hong Kong website.

Airport ( HKG ) 

Big Buddha on Lantau Island

Botanic Gardens

Disney Hong Kong

Government House  

Hong Kong Museum of History (TST)

Jade Market at Jordan

Peninsula Hotel Lobby  ( always worth a look )  

Star Ferry ride across Victoria Harbour

The Peak ( take the tram or a double decker bus ride to the top )

Tram ride across Hong Kong Island from west to east or vice versa

Temple Street and the Tin Hau Temple at Jordan

Walled Village in Kam Tin