Lived in Hong Kong for about 4 years. I'm sure you've come across the obvious places to go and see, so I'll just mention a few hidden gems that might not get a lot of recognition on tourist websites
Sai Kung Penninsula - great place to go hiking, kayaking, some nice beaches or enjoying nature. Beautiful scenery
Golden Computer Center in Sham Shui Po - best place in Hong Kong to buy electronics/technology.
Cheng Chau Island - it's about 20 minutes from the Central Ferry terminal. Beaches, restaurants and Temples. A nice place to go if you want to get away from the skyscrapers
Royal Pacific Hotel and Tower is a great place to stay. On the edge of TST, near MTR stations, and Star Ferry to cross the harbour to Hong Kong Island.
The T Hotel is on the west side on Hong Kong Island, near the University. Not a great location, but they make up for it by having a great view, free wifi, awesome service, free breakfast, free shuttle to common locations etc highly recommended
http://www.vtc.edu.hk/thotel/index.html