For Kowloon, you can try 鸿星海鲜酒家 in Harbour City. Was there last month. Not bad. ;p
There is a less "high-class" one in a commercial building opposite of the Royal Garden Hotel in Kowloon. Not bad also, but I forgot the name. Just go to Royal Garden Hotel and ask the front desk to tell you about the dim sum place opposite their hotel.