No offense to Twilight fanatics out there. But as much as possible I hope you'd try to avoid vampire stories. I'm a vampire fan too (way before they began to glisten), but being bombarded with vampire stories everywhere on the net everytime, I kinda start hating myself for loving these immortal mythical creatures.
Werewolves may be better. I never really liked them but recently I kind of had a change of heart. But yeah, I agree, it kinda sounds a little like X-men so maybe you can try putting a little twist to it. Wish you luck.