I read a lot of vampire romances (seriously, a lot), and it is hard for me to choose one favorite. One of my absolute favorites, though, would be Halfway to the Grave by Jeaniene Frost . The main characters, Cat, a half-vampire out for revenge, and Bones, a vampire bounty hunter, are a great couple and the plot is a good mix of romance and suspense. Their story continues in three more books (so far), and is one of the best series in paranormal romance. Check it out!
The other books in the series because I know you'll want to read them: