
Every book sets its own standards for how explicit or how subtle, and sometimes you figure it out by doing it wrong. If it's too graphic, it verges on porn, and if it's too discreet, it feels prudish or even silly. Obviously, noir or hard-boiled stories allow more process than a cozy or traditional, but even then, you have a little...er, wiggle room.
Remember the Frank Zappa song "What's the Ugliest Part of Your Body?" The punch line is "I think it's your mind." Well, sex scenes really aren't about the choreography of who does what to whom and how much how often as much as they're about the emotions your characters experience.
If you're just putting tab A into slot B and folding appendage C over corner D, you're writing porn. Janet Evanovich discussed Stephanie Plum's frolics with a fair amount of detail, but also with large doses of humor. If you add humor, which chick lit romance writers--Jennifer Crusie, Jayne Anne Krentz, and Rachel Gibson, to name a few--do, it's much better. I admit, I read chick lit for the terrific dialogue. Yeah, sounds like when we were in college and claimed we read Playboy for the interviews, doesn't it?
Dennis Lehane's novels featuring Patrick Kenzie and Angie Gennaro never describe their activities in much detail, but have any readers ever doubted for a second that they had a very hot sex life? Don Winslow, on the other hand, has a scene in California Fire and Life (one of my favorite crime novels) with Jack Wade and Letty Del Rio that tells you everything you never wanted to know...and it's perfect. These two have blamed themselves for ruining their relationship and splitting up years before, and now they discover how miserable they've been ever since. The scene is in Jack's head, and, graphic as it gets, it's so vulnerable it hurts to read it.
It's all about context, and sometimes you aren't the best judge. My first few books had some fairly explicit scenes, but I've moved away from that...until this one. In the WIP, Chris and Meg have their first really serious fight over a case and are trying to handle a situation they both botched in their previous marriages. Eventually, there's a hot make-up/apology sex scene. That scene didn't appear in my first draft, but my revising showed me it had to be there. In alternate drafts, it has become more and more graphic, and I've tried it from both Meg's and Chris's POV. I've even put it in and taken it out several times. I've tried it as a flashback, too, and it still doesn't satisfy me.
One more revision and it will go to beta readers. I'm already looking forward to their opinions and may even include three separate drafts of that scene: Meg's, Chris's, and none.
Who ever knew that sex could be so hard?