I don't think you can find a single perfect example because that will be based on that particular company in that particular industry. But what you can do is look for a series of landing page best practices. My book, The Best Damn Web Marketing Checklist, Period! includes many of those best practices that directly affect PPC as well as other areas of marketing. You can also find the free cheat sheet at www.webmarketingchecklist.com. You also might want to check out this article here: http://searchengineland.com/why-my-optimized-landing-pages-trump-your-seo-and-ppc-landing-pages-everytime-167430 as well as the book Landing Page Optimization by Tim Ash.