After walking the red carpet at the New York City premiere of We Bought a Zoo, co-stars Scarlett Johansson (in Dolce & Gabbana) and Elle Fanning (in Louis Vuitton) headed to the Royalton Holtel to kick up their heels at the after-party. If Johansson hadn't pursued acting, what would she be doing now? "I probably would have been a doctor," the actress told reporters. "I love everything having to do with medicine." Click through to see Jessica Biel, Molly Sims and more stars at last night's hottest parties!