Dubai

While the scorching outdoors are off-limits, Dubai’s abundant indoor playgrounds will have AC on full blast. Shop at the largest mall in the world (a destination in itself); ride to the top of the world’s tallest building, Burj Khalifa; and ski down an indoor snow-covered mountain. Hotels are heavily discounted and traffic is nonexistent — but avoid traveling during Ramadan (May 5 through June 4), when you can’t drink water in public.