In general, I want them separate. If I want to read erotica/porn, then I go to asstr.
The thing with depicting sex in a story is that its like depicting brushing teeth, peeing, taking a dump, or any other activity that's usually private. Unless its plot-relevant, I don't want to read about it. Even romances can get away with no sex scenes, unless the sex scene happens to have an impact in the story (for example, one of the persons involved turns out to be abusive, enough to cause the other person to not want sex, which is significant in a relationship).
Take, for instance, Mario Puzo's The Godfather. It was a story about family, crime and corruption. The size of one of the character's dong is unimportant to the plot, as is the size of one of the character's vagina. But Puzo spends at least 11 pages detailing how big the woman's vagina is, as well as several pages scattered throughout the book on how big the character's penis is. Seriously, WTF? Puzo spends as much time describing their genitalia as the backgrounds of the main characters. Reading it annoyed me to no end.
Several novels I've written have had sex in them, but I never actually describe the actual physical act. I'll set up my characters in such a way that it's obvious they're about to go at it, then skip to the next scene, often a conversation held in bed. Here's why:
1) Sex scenes are a pace killer. Have to take time out and describe sex to someone rather than get on with the plot. 2) Brief allusions can imply and suggest a lot more than an actual scene. 3) Leaving the physical act in the imagination of the reader is better as my particular idea of good sex might not be someone else's. 4) The better sex scenes I've read tend to be sparse on detail. Reading about the physiology of throbbing hot swords thrusting into readily accepting vessels sounds like the voice of an adolescent that hasn't actually had sex.