I usually read only one book. However, I have a tradition that goes back to High School that I pick up once in a while.
1 book at work/school/on the road. A paperback book
1 book at home. A Hardcover.
I haven't followed it until recently on my cruise. I'd been reading Wolves of the Calla, but took Children of Dune and God Emperor of Dune on the boat. Also, now that I'm back and my copy of Harry Potter and the Deathly Hollows has arrived, it's become three books because I want to finish this before some ahole spoils it.