Umm.. Patricia Cornwell...haven't read any of her works but I've been meaning to. Tracy Chevalier if you are interested in historical fiction. Janet Evanovich if you are into crime fiction and humour.
I would reccommmend Paulo Coelho, The Alchemist is a good start.
He and Courtenay share the same sense of human emotion and drama.
Perhaps also Gabriel Garcia Marquez, but he's not really light reading, however he has that Courtenay-esq sense of sweeping history and family sagas as well.
- Love in the Time of Cholera or 100 Years of Solitude.