1. Vampires are old. Generally women aren't into naive men. We like men who are experienced, worldly and wise. Vampires, for the most part, have had time to travel, experience the world. Chances are good that you aren't going to have to deal with a vamp buying a red convertible trying to regain his youth. The clincher here is that unlike old living men, vampires remain crazy sexy.
2. The undead seem to mate for
3. The tortured soul. Vampires always come off as having a tortured soul. No one understands them. No one except their chosen lady that is. She is the only one who really gets him. She's the only person he can open up to and be his charming self. It's cliched, but we like that. It makes us feel special...deal with it guys.
4. Vampires are romantic. It's like they've got a whole team of scriptwriters feeding them lines like "You're my life now" and "all I did was watch you sleep, but it was the best night of my life". I mean how is a regular unscripted guy supposed to compete with that?
5. Last, but not least is that vampires are dead sexy. So long as you don't need a guy with a tan, you can't get much hotter than the living dead.