One of my best HKG seafood experiences was taking the 1 hour ferry to Cheung Chau island, buying fresh seafood in tanks at the dock, and having the dockside restaurant prepare it. It helps if you speak Cantonese, but a little good humor goes a long way here.

There may be someone killing and preparing chickens about 5 feet from some tables, so you may want to choose carefuly where you sit. I generally face my wife and kids toward the water to avoid them converting instantly to vegetarians.

For high end seafood, some people thing the standards are Yu, in the Intercontinental, and the Lobster Bar in the Island Shangri-La. Hotel resturants in the high end hotels generally have a very high quality product in HKG, unlike a lot of other cities.
Rich