I think part of the draw is also the mystery of the characters.  Since vampires and other such creatures don't really exist, they draw a mystery and an unknown quality about them.  Writers can create a fictional history for their characters that has enough standard rules for the audience to be familiar with it.  They feel like they know these characters before they are even introduced.  For instance, most vampire stories insist that vampires are immortal.  Many of these tails suggest that vampires cannot step into the sunlight.  Stories that differ from these norms must still address them because the audience will expect it.  Stories about vampires and werewolves can be both new and familiar at the same time. 

I would suggest that vampires are popular given the new interest based upon novels which depict the "creatures." I remember when "Interview With a Vampire" first came out (the movie) and people went "crazy" for vampires. Girls wanted Brad Pitt to bite them in the same way teenagers today wish Robert Pattison would bite them. It helps that directors cast very attractive people to play the characters. So, I would second the sexuality of the vampire as being attractive.

I would say that a big draw with a lot of these supernatural creatures is that they come with supernatural powers. As humans, we may dream of having super powers, but we will never have them. In the Twilight books, each of the vampires had some kind of special ability. We would love to know someone who has a special ability, even if we can't have one for ourselves, so we like to believe that there are people out there like these vampires that really exist. We wish we could have these special abilities, but we can't, so we have to be satisfied with reading about people who do.

I agree with what post #8 says about the sexual aspect. Not only is it dangerous, which heightens the sexuality, but there is also the dominance factor. These supernatural beings have power over their mere human counterparts, and that appeals to many readers.

I'm going to go with the psychological carnal response, because I think that's the most powerful (though also most base) source of our, er, "appreciation" of things. Vampires and werewolves are a prime example of exploring those urges through literature and film. It's all about the animalistic urges lurking within us! Stay with me:

Vampires- Anyone who has studied vampire literature in depth--or monitored a teenage girl's heart rate while watching Robert Pattinson walk across a movie screen--knows that sexual feelings are a big part of it. The desire of a vampire to feed, usually on attractive, innocent young maidens, is dangerous and nearly uncontrollable. Though there's violence behind it, this idea is part of the human sex drive. The lust to possess is the same thing that drives the vampire to hunt and kill. And let's face it, humans are interested in pretty much everything that's related to the human sex drive!

Werewolves- Most werewolves are more overtly violent rather than sexual in nature (though feel free to debate me on that). This, again, mirrors a darker side of human nature. Being civilized requires that we quiet the beast within, that we resist the urge to use violence for our desired ends. Werewolves fulfill that latent desire to give up the human side in order to become beastlike, and therefore have the convenient inability to control or remember our actions. The werewolf is sheer power and terror. Deep down (I'm arguing), most people have wanted that at some point in time. But we're civilized. So we read and watch werewolves do their thing instead of going crazy. As post 6 reminds us, "supernatural forces relate to the seemingly inevitable outcome of a creature's humanity being overpowered by their monstrosity." We live that idea through vampire/werewolf stores. 

I would venture this proposal: Vampires, Zombies, and the lot of monster-humans are especially interesting to people today because there is a rather special sense of change in today's world, change accompanied by mystery. 

The advancement of computer technology coupled with the globalization of industry and a world-wide economic downturn has set the stage for a major shift in our lives. The degree of potential change does not automatically translate into big change, of course. Thirty years from now things may look very much the same as they looked five years ago. 

The idea is interesting to me though to wonder if zombie afficianados feel, somewhere deep down, that what it means to be "human" is now being stretched and questioned in a general and generally cultural way. 

Transformation is at the heart of vampire and zombie stories. Could it be that our ideas of what we will become has become somewhat garbled and one response to this, in young people especially (who have yet to create lives for themselves) is a fascination with magical transformation? 

These transformations are, after all, a lot like discoveries, revelations of a true and potent self. 

I really think that most people feel a draw to be a part of something bigger than they are... something more than just ordinary.  Whether a person relates to the vampire of the one hunting/ fighting the creature, it gives rise to the extraordinary.

This isn't really a recent phenomenon. The supernatural has always held a very strong appeal for the human imagination--it's been going on for centuries. The difference is that now, supernatural characters are often viewed sympathetically. What used to be portrayed as pure evil is often given a more human perspective.