Hmmm, I've read my share of romance but kind of moved on to Urban Fantasy (Charlaine Harris, Rob Thurman, etc.) I am generally not a fan of long sex scenes in romance novels (I do some skimming) but for a tortured bad boy type Shannon McKenna is pretty good at the alpha male. Seth from Behind Closed Doors tends to be a favorite when the conversation about alpha males comes up! Plenty of sex scenes, just a warning.
If you can do a vampire story, Sunshine by Robin McKinley. Enjoyed both hero and heroine, though this one could have used a sequel it is really good.