First of all, I found that sex scene absolutely atrocious. It seems to me that Tanith Lee obviously never intended to read that passage aloud because the words just sound all wrong and smashed together in a haphazard way. It doesn't flow, it doesn't drag me along with it the way a good sex scene in a book should.

The problem is that, in trying to find something really good, I keep going back to books that are properly styled erotica. I'm not sure if there are a lot of good sex scenes in books that aren't about sex.

When I think about good sex scenes, I think of L'Histoire d'O, ?????? ? ???????, or La Nouvelle Justine, and I'm not sure if it's fair to compare books written expressly to describe sex with books where sex is incidental to a broader story.

There are some scenes I hesitate to mention for other reasons, such as Lolita, where the sex scene is not as graphic due to the words used. In order to really find it "exciting", though, I also need to do mentally what Stanley Kubrick did explicitly in his film adaptation - make Lolita older than she really was. Perhaps one of the best examples I can come up with is American Psycho, which has decent enough sex scenes if you take out the murder component (perhaps others don't need to ignore the murder but that sort of thing doesn't really turn me on, particularly if it's not ritualistic).

I suspect that my choice of reading may also be contributing to the situation. Of the more contemporary authors that I read, most tend to either the philosophic (like Kundera, Eco, Mahfouz or Sartre) or the hallucinogenic (Hunter S. Thompson, Viktor Pelevin). Bukowski writes about sex, but he intentionally makes his descriptions unpleasant (read into that what you will).