I usually have one novel that is part of a series or books all by the same author (I did Anne McCaffrey, Isaac Asimov, Margaret Atwood, etc and am on Stephen King's Dark Tower series now) and a non-fiction book of some sort, usually history or some such, sociology, etc. I also often have something I have read before on my bedside table. Sometimes poetry or Jane Austen.
I just got a Nook awhile back and have the Dark Tower series on that as well as a bunch of knitting books. I also downloaded a ton of old books from Project Gutenberg, so I can always dip into classics that I am either re-reading or have always meant to read. I finished some Proust and Goethe recently because they were there. I had thought they would be boring but I really enjoyed the Proust. Live and learn, lol.