I think the current spate of vampire novels is written with teenage girls in mind, not intelligent adults. At least it gets them reading, but then girls were never the problem anyway as the most reluctant readers are boys.
I still think that Dracula and Lestat are sexy and that is their main appeal: the sinking of fangs into the helpless female (Dracula; Lestat was a little more varied in taste) mimics the sex act, especially when remembering that B. Stoker wrote at a time when sex could only be suggested. I used to love the Hammer films: the moment when Dracula wrapped his clock around the swooning, hypnotised female and slowly went in for the jugular....swooon
Vampires are definitely hugely sexy. I haven't read the recent spate of books: Twilight and Co, considering them the undead equivalent of Janet and John.
That nymphomaniac succubus novel sounds like fun!