Endowed with the largest private fortunes of their day, cousins John Jacob Astor IV and William Waldorf Astor lived incomparably privileged lives in the blaze of public attention. For three decades around the turn of the nineteenth century, they vied for dominance of high society, creating the grandest hotels the world had ever seen-perfect fusions of excess and efficiency that became America's castles of capitalism. In this fascinating anecdotal...