The only fitting way to celebrate Valentino's new London exhibition would be with a celebrity-studded fete — where, of course, everyone is wearing Valentino's gorgeous confections. That was at least true for the always-stylish Alexa Chung and Olivia Palermo, both of whom joined Valentino at the opening of Valentino: Master of Couture. Both looks were a testament to the range of Valentino's beautifully feminine collections. While Alexa's look was a playful riff on cocktail couture, balancing a delicate lacy bodice with a bright neoprene skirt and a demure bow-trimmed waist, Olivia's catered to a sexier side. With a semisheer lace skirt and halter neckline, Olivia's dress was equal parts elegant, ladylike, and just a little more sultry than Alexa's sweet confection. Of course, a big part of the results were the finishing touches employed by both style setters. Alexa stuck to her charming aesthetic, adding in a top-handle handbag and a pair of ankle-strap Valentino pumps. Olivia gave her gown eclectic edge with a statement necklace, cropped jacket, and high-wattage heels. Now it's time to weigh in — whose Valentino do you prefer?