Back in September, during New York Fashion Week, I caught up with Blake Lively at Marchesa’s spring 2010 presentation and pondered what the Gossip Girl star might wear from the collection of slyly sexy confections. From the 25 looks, I chose two favorites—one short and frothy, one long and airy, both with one-shoulder styling. You seemed split down the middle, but Blake knew exactly which one she liked best. For Tuesday’s premiere of Where the...