In general, I want sex scenes to follow through on expectations set up by the rest of the movie or book. Some stories don't set sex up to be a climactic event or turning point. In other stories, sex is a climax even if it doesn't result in orgasm.
I think most readers accept sex with a positive aura in fiction because fiction is to some extent an escape from life; expectations are set up and met one way or the other, lines between good and evil are clearer, and maybe the sex is better.
Sex scenes don't necessarily have to be about the sex. They're still called sex scenes because they include sex, but arguably any scene that's part of a narrative (story) should be about more than what's taking place on the surface. Characters may be saying or doing one thing, but a subtext is moving forward at the same time.
Scenes satisfy me when they serve the larger story being told. If they don't serve the story, they should be reworked or cut.