Thanks for starting this thread, tyd! I LOVE to read and to write as well, so I am always interested in hearing what others enjoy.

I love the Kushiel's Legacy series by Jacqueline Carey. So far there are six books in the series: Kushiel's Dart, Kushiel's Chosen, Kushiel's Avatar, Kushiel's Scion, Kushiel's Justice and Kushiel's Mercy (coming out this summer). The books are kind of complicated, but I'll do my best in describing them.
The books take place on a world similar to Renaissance Europe. The main country is Terre d'Ange (France) and the people there are the descendants of fallen angels. Their main god is Eula, who told his people to "love as thou wilt." One of the fallen angels is Naamah, whose worshippers are forms of sacred prostitutes. All forms of sexuality are accepted and the only real crime is rape.
The book is told in the first person by Phedre, who is in the service of Naamah. She is an anguissette, a sexual masochist. She has a red mote in her left eye (Kushiel's dart) that shows others that she is basically a pain slut. She later gets a bodyguard, Joscelin, a kind of warrior monk, who can't understand how Phedre can equate pain with pleasure and she can't understand why he can't see that.

This is the series that proved to me that I am indeed a pain slut. In one of the books (I believe it is the third one) Phedre becomes lost on her path and isn't sure what she should do. She's in the middle of a spiritual crisis. She goes to one of Kushiel's temple, where she is flogged by one of the priests there. The scene is not erotic and is not portrayed as such, yet it turned me on something fierce, like I was the one tied to the whipping post. BTW, Phedre likes the pain that draws blood, makes her see red, etc.

Carey has done her angel research and it shows. For example, Naamah prostitutes herself when she and her fellow fallen angels were wandering as they tried to find a home for themselves. According to the Kabbahla, Naamah was one of the three angels of prostitution. Phedre goes to Kushiel's temple for punishment for faltering on her path. According to the Midrash Konen Kushiel was an angel of punishment.

If you like long, complex fantasy novels with lots of adventure, political intrigue and BDSM, then I would recommend the Kushiel's Legacy series.