I'm heading for India today, flying to Bangalore via Frankfurt, around 33 hours of travel, give or take. I'm all packed and ready except for "booking my flight," which is to say making my final choice of reading materials to carry, always a difficult decision. Traveling in coach (alas) doesn't provide much space or an external power supply for extended computer use, so I tend to mostly sleep when I'm supposed to (on destination time to counter jet lag), and to otherwise read. I read fast so I need to carry several books, which means mass-market paperbacks for the most part.
Fortunately I have a lot of books around the house, many of which I bought some time ago and didn't read for some reason at the time, so I often find some unread "surprises." Two for the computer bag on this trip are Steven Baxter's Evolution and Dava Sobel's Longitude. Evolution is a sort of fictionalized counterpoint to Dawkins' The Ancestor's Tale, which is a huge trade paperback and will thus stay home (I'm about 135 million years back in that book, still a ways to go). Evolution is a long science-based narrative journey through pre-human, human, and post-human evolution which gets mixed reviews on Amazon, but those who like it seem to really like it. I think I will too - I've read and enjoyed several of Baxter's other "hard SF" novels. But I've got some backups in the checked luggage just in case.