In the landscape of Long Island's Greek restaurants, Alexandros is Mount Olympus: high above the rest and revered. The Greek revival recently relocated to this address from Miller Place, intact andin style. Part dining room, part bar, it's a warm, festive neighborhood spot and inviting for anyone who has experienced one too many leaden moussakas or air-dried baklavas; and for all devotees of fresh whole fish and juicy steaks. Reliefs reflecting ancient and mythological scenes decorate the openhanded eatery. The gods must be smiling.