Hotels, like life and boxes of chocolate, are unpredictable. You never really know what you're going to get. But what if you could inspect the view from your hotel-room balcony, stroll down surrounding streets, and check out the size of the pool—all before you check in? A set of innovative online resources, from video vaults to social networks, can help you achieve a satisfying feeling of deja vu—and avoid any unpleasant surprises—when you walk into your next oceanview suite or deluxe guest room.