The hardest thing about packing for a vacation is figuring out what reading material to bring. Especially if I have just finished a book, leaving myself with a clean slate. Can't bring too many, as I will have plenty of activity and not a large amount of time for reading. Can't bring too few as I need enough to cover the flights at least. Also I have to make sure I pick something I am not going to hate, because I cannot just put it down and go back to my bookshelf for something else (I could go to a bookstore though, but that's a baaaaad idea for me).
Generally, while on vacation I read at three different classes of time. To fall asleep. First thing in the morning while I am having breakfast, although usually this is time for the N.Y. Times. And while in transit (planes, trains, and automobiles).
Am thinking one cheap thriller type book. One more serious fiction book. And a non-fiction book.
Won't finish any of them though.