Paris Hilton and Nicky Hilton Coachella regulars Paris Hilton and Nicky Hilton opted for simple, bohemian-inspired gear for the weekend. Katy Perry Katy Perry mixed prints — and some ketchup and mustard — with her Coachella outfit. Diane Kruger and Joshua Jackson We’re not sold on Diane Kruger’s ruffled skirt, but we’re totally digging her…