I'm seeing a lot of more established writers weighing in on how to write sex scenes over the past week, so thought I'd serve up my two cents, FWIW.
There is a perception that women want a little steam in their romances, but it has long been my contention that a well written story doesn't need to show a lot of body parts. I recently read a number of romances (my favorites are the historicals) where the story is about how the heroine strives to be a societal parriah by seeking out to "ruin" herself, these under the guise of "fractured fairy tales" (a number of authors seem to be jumping on this bandwagon). The focus of these stories isn't the story itself, it's how Jane Eyre loses her virginity.
Reading a romance can be a lot like buying a magazine, in these terms, a Playboy, or a Penthouse, or a Hustler. I'm not adverse to the Playboy versions - after all, there are some good stories to offset the pictures, aren't there? (that's what I'm told anyway.) There are erotica lines, which would fall into the Hustler category. But what I've seen lately is more of the Penthouse variety romance. Lots of gratuitous sex disguised as romance. I grew up reading Victoria Holt, and in all but one of her novels, there isn't even a reference to sex, and yet its easy to fall in love with the hero even without him taking his clothes off. These are novels we can hand to our teenage daughters, rather than the newer variety of sex-equals-love that I've been reading. When I was a teenager, you couldn't find these types of books in the library. There is very little plot development, and for a historical to be true to the time period, there are standards that should be observed. Yes, times have changed, but is this the message we want to send to our children? (okay, off my moral soapbox.)
I don't object to a little sex in my stories. You'll find it in my own novels. In fact, I had a friend of mine come up to me and say how much she enjoyed the steamier sections of Intimate Distance. Certainly, I'm not an authority, and likely I haven't always gotten it right myself. There seems to be a market for sex inside the story. My objection is sacrificing the story in favor of the sex.
When I've met with agents and/or publishers at conference pitch sessions, I ask them if the market demands sex in romance novels. The answer is almost categorically no. If it has a place in the story, that's one thing - if it advances the plot - not as a gratuitous intrusion.
Women enjoy sex, too. Clearly there's a market for the erotica romances, but I've been seeing more of the "Penthouse" variety stories that are not marketed as erotica, they're marketed as romance novels.
My favorite authors are the ones that can weave a story, not rush me into the bedroom and tell me that love is dependent upon sex.