Hi Richard,The gambling vessels are generally anchored to the east of Victoria Harbour by Kai tak runway. The North Point ferry is about the closest vantage point although you might be able to get out to the cruise terminal (newish white elephant) for a view although I cannot say how good that would be.
A very good vantage point is on the road leading to the South Horizons warehouse showrooms. patience required but quite close up. Some of the stores on upper levels of South horizons have good vantage points right over the lamma channel. I would say for inbound and outbound this may be one of the best (non security spots) for viewing vessels.
OCEAN Park would also offer good vantage point more or less opposite the pilot boarding stn. Both this place and South Horizons have good bus services but the former is a lesser frequency, about 30 mins headway.
The Mtr isnt up and running as yet but will provide an ideal transport prospect to both locations.
You could go to Tsing Yi to overlook the shipyards but as I havent been that way for years I am not sure how slack security is these days.
So in a Nutshell, north point and ferry if running, Ocean Terminal and Kai tack terminal, and for vessels on the move southern shores of HK Island.
Regards G.