1: Aftermath by Al Steiner This was one of the first stories I read on this site, and continues to be one of my favorites. It's a compelling story about the human nature in the face of a disaster. It is a sex story, but the sex in very well integrated in the plot, to the point where the story could be considered non-pornography by just removing the most visual details.
2: The Invention by Dark Paladin The sheer erotism on this story is amazing. I love how the characters are forced to act on their impulses, showing how close we are to our base instincts. I don't like mind-control stories, but this could be qualified as a mind-discontrol one.