Kourtney: Kim Is Herself Around Kris Humphries

With Kim Kardashian and fiancé Kris Humphries due to head down the aisle, her sister Kourtney Kardashian and Scott Disick say that Humphries brings out the best in Kim."He fits in [with the family] already. I think they're just themselves, and I think that's the most important thing," Kourtney, 32, told PEOPLE at Disick's 28th birthday party at Las Vegas's Gallery Nightclub over the weekend."Kim