The Four Seasons (Langkawi, Malaysia): Perhaps the most stunning beach in Malaysia, this wide gorgeous stretch of white sand looks out onto crystal-clear, deep-blue waters. Even if you can't afford a room at the resort, I highly recommend a cocktail at their deliciously exotic beachside bar so you can get a chance to enjoy the view.
Kampung Juara (Tioman Island, Malaysia): This beach is what they mean when they say isolated. Be prepared to live like Robinson Crusoe -- in tiny huts, many with no electricity at all. But, oh, the beach! Most visitors don't get to this part of the island, so many times you can have it all to yourself.
Cherating (Malaysia): If you're a leatherback turtle, you'll think the best beach in the world is just north of Cherating. Every spring and summer, these giant sea creatures come ashore to lay their eggs, so if you're in town from May to June you might catch a look at the hatchlings. Meanwhile, during the turtles' off season, international windsurfing and water-board enthusiasts gather annually for competitions at this world-famous spot.