The Sookie Stackhouse novels are probably my favorite series. I'd have to say that
Club Dead (book 3) is my favorite, but I do love the later books where Eric becomes a bigger character and Quinn is introduced. I've gotten my mom to read all the books and my best friend has gone through the first four.
If you are looking to start the series or you already love it, but don't own any of the books, I'd recommend getting one of the box sets. There are two: books 1-7 and 1-8. Last Christmas I got books 1-7 in a set and it was great because I wouldn't have to wait to start the next one. If you're interested in either one, I believe Amazon has the best price.
Oh, the Black Dagger Brotherhood.
My mom randomly bought the first book and I decided that I would read it when she finished. Well, she was taking her sweet time with it and I couldn't wait any longer, so one Saturday I ended up reading it in just a couple of hours; it was so addicting! Once she finishes it, I'm going to re-read it. I haven't read any of the others in the series, but there's a box set that I'm hoping to get for Christmas.