That long, long coastline stretching from the Gulf of Tonkin to the Gulf of Thailand simply begs to be explored. About halfway down, you’ll find the laid-back city of Da Nang—an ideal jumping-off point for excursions to three UNESCO World Heritage sites—and far to the southwest, the up-and-coming island destination of Phu Quoc. For big-city buzz, there’s always Hanoi, the vibrant capital where old and new collide in enthralling ways.