This morning in San Francisco, Apple announced two new iPhones—the 6s and 6s Plus. Wondering if you should upgrade this month when the phones become available for preorder September 12? "The only thing that has changed with iPhone 6s and iPhone 6s Plus is everything—3D Touch lets users interact with iPhone in entirely new and fun ways, and the innovative Live Photos brings your pictures to life," said Philip Schiller, Apple's senior vice president of worldwide marketing. "These are the most…