Getting away from the crowds in Hong Kong is easy. I did this Aberdeen 香港仔 walk on February 12, 2013, the third day of Chinese new year and a public holiday, and there was hardly anyone around.
It's a loop that begins in Aberdeen Country Park, past the lower and upper reservoirs, up Tin Wan Hill and down Peel Rise back to Aberdeen. It takes around 3.5 hours and is very easy walking apart from a couple of steep flights of steps.