Mathew Rosengart arrives on the rooftop restaurant of the Waldorf Astoria Beverly Hills wearing a wheaten wool coat from Barney’s, steeled against the early February cold snap that has whipped across Los Angeles. The sky is awash in Monet watercolors, the twinkling lights of Beverly Hills are aglitter. “It’s imperfect, and the clichés are often true, but there is something magical about L.A.