Anaïs Nin.

Anne Rice. Any of the vampire novels.

Laurel K. Hamilton. Book 5 of the Anita Blake Series onwards.
She may employ every stereotype in the explicit scenes but they aren't boring - and she's creative as hell. (She also gets into BDSM and Poly in later novels).
Her books are solidly written.

Not unadulterated erotica, but there are some well written bits in "The Cruel Sea" and also "Lolita"

Facts hurt. Romance is one of the major selling genres and those sales are particularly good for Romance of an erotic nature. So, if sales are good, how does this fact hurt? Because sales are literally guaranteed and because those doing the buying are not particularly picky, the genre supports the largest number of hacks per capita. That guarantee of sales attracts writers who are in the craft for all the wrong reasons. That doesn't mean there aren't any writers of erotica who are concerned about the quality of their craft, it just means that they are in the minority. So, in answer to your question, I have to attach some qualifiers. First, I am not one who normally reads Romance of any kind and erotic writing does not make my wheels spin. Second, my opinion may be a little more well considered than some, but it is still only worth what I'm charging you. $0.00

Aside from some of the classics written even before I was born, I cannot think of a single Romance novel I've read, admittedly most not in their entirety, that had any substance, literary quality, or was worth the effort or the cost involved in picking it up. However, I am confident that there must be a few contemporary examples worth reading out there.

nope. the genre lends itself to bad, bad writing, mostly having to do with bad pacing and the desperate attempt to find new names for body parts without getting ridiculous. there is a nice page, give or take, in ragtime, that is rather erotic and yet well done. it's in one of the emma goldman chapters. i don't think that sort of thing can be sustained for very long, such as for a whole story.

g