Before you travel, always check to see what the national holiday schedule is for your destination. I know this may be shocking, but the rest of the world does not have the same holidays as the United States.
On July 1, I was in Hong Kong for a day just to see the sights. I came to find out that July 1 is the anniversary of the day that control of Hong Kong was handed over by the British to the Chinese. It is a national holiday for Hong Kong, and as a result the entire town is packed since no one has to work.
It was sheer luck that I was in Hong Kong on that day, because I was completely oblivious to the holiday before I arrived. I would not have had it any other way though. The town was amazing to see, and the mixture of cultures made me feel right at home.
If you are going to Hong Kong, you must go to The Peak, ride the Star Ferry, watch the light show at night, and stroll up Nathan Road. They are the things in my opinion that show the true side of the city.
Before you leave the city, make sure you are able to watch the sunset reflect off the of the buildings and water. I was able to witness it with 10,000 other people around me, and it had to be the highlight of my time in Hong Kong.