While I've dined in more impressive Hong-Kong style banquet palaces, I haven't had better dim sum anywhere in the United States.
House of Louie is situated in the middle of an unassuming strip mall off the I-10 freeway and Grand Ave. exit. in Covina. HoL is a great place to meet for decent Chinese food if you are east of Los Angeles and past Monterey Park and Alhambra.
Although the selection is not as big as Sam Woo or Empress Pavillion, the quality supercedes your typical dim sum cart selection. To get a quality experience, make sure you ask for a booth. Then start with the Fried Butterfly Shrimp, Sticky Rice in Lotus Leaf and Football (they'll know what you're talking about). My method is to start with the fried selections then go for the steamers such as Siu Mai, Ha Gow, Stuffed Egg Plant and Shrimp Rice Noodle. Make sure you have iced tea or their wonderful oolong tea (not the usual yucky black tea that you get from Sam Woo) to go with your meal. Then top it all off with Sweet Tofu. Yum!!!!!
By the way, drink all the tea that you want because they have a very clean bathroom.