LOVE Stephanie Plum!!! She is one of my favorite series to read.
I also like Harris' vamp series, but her others are also good.
I still carry around Anne Rice's vampire chronicles with me, though I haven't read any of them in a very long time.
I like series because I love getting to know the characters and following them through their lives. I was a little dismayed when Anne Rice ended her vampire novels, but it was time for a new phase in her life, I guess.
I haven't gotten around to Discworld yet, but I have been badgered to do so; that and the Dresden Files I think they are called?
I love the Southern Vampire series by Charlaine Harris. In addition Janet Evanovich´s "Stephanie Plum" series has been accompanying me for the last decade, but it starts to get too repetitiv even for me. Every once in a while I fall back toTerry Pratchett´s dicsworld novels. In the YA section I adore Percy Jackson´s adventures