Put me in the camp of flitting from genre to genre (mystery/Thriller, History, "Modern Lit" Sci-fi/Fantasy) and rarely if ever reading two books in the same series back to back. Have to have my variety.
I am rather anal about having to read series in the order of publication. That's why some of these Nordic thrillers sort of drive me a bit crazy since publishers often begin translating/releasing books out of order (i.e. the Harry Hole Series by Jo Nesbo - excellent series though).
Though for as little as I can sometimes remember of previous books once I get around to reading the next volume in a series, maybe I shouldn't worry so much about reading them in order