Can't think how I missed this thread first time around! Yes, I also vote for Antoniou, she writes real characters and the story arcs that run through the later books are also compelling. If you want to start anywhere, either that first one or if you like your porn with plot, try "The Reunion," which manages to keep several real plot lines going along with plenty of hot BDSM sex. If she's got one fault, it's that she expects everyone to share her fetish for detail-perfect domestic service, but we all think our pet kink is the best.
I met her at a fetish market some years back and got a signed copy of "The Academy," it might be one of the things I'd save in a fire.