I have stayed at the Marriott on the Kowloon side, it is virtually on the harbor, a short walk to the Peninsula Hotel, the harbor ferris and the main shopping street. The Kowloon side is also where the train from the airport arrives in to, definitely take the train into HK if you are flying in as cabs are expensive and slower. Marriott is a good value and upscale western style hotel. The Marriott and Shangri-la on the HK side are considerably more upscale and correspondingly more expensive.
Spending my money, I would stay at Marriott on Kowloon side and enjoy the ferry. While In HK take the incline railway up to Victoria Peak, the view is not to be missed. almost 7 years ago