I don't listen to audiobooks on tour, but I do listen to a ton at work. Here's some I have enjoyed:
Snow Crash
Memoirs of a Geisha
Slaughterhouse Five
Cat's Cradle
The Curious Incident of the Dog at Midnight
Running with Scissors
All of the Harry Potter books ( get the one's narrated by Jim Dale, he is amazing)
White Tiger
His Dark Materials trilogy
War and Peace (it's looooong, which would be great for a trip)