Oh boy... only 2 days
That's very llittle for a place such as Hong Kong
Hmm... it's been a couple of years since I've lived there, but my suggestions would be:
For nightlife: try Wanchai area and Lan Quai Fong.
Back in the days when I used to live in Hong Kong my favorite place to have dinner, or just for drinks and live jazz music: Island Shangri La, Restaurant Petrus (make sure you've got a good credit card
Absolute killer view over a good part of Hong Kong from the 56th floor of a hotel located on the hillside already.
For casual seafood lunches try Lamma island.
Things you may want to see/do (gotta have a sightseeing program, right?)
- The Peak on Hong Kong island for great views.
- The big buddha on Lantau (will cost you a good deal of time though)
- Star Ferry ride
- Enjoy everything else - Hong Kong (not only the island Hong Kong, but all of it) is full of interesting things to see. Enjoy the contrasts that meet you at every corner, have fun on the many markets, enjoy the architecture (both, traditional and new). Being there for Chinese New Year is a great bonus.