I've been a fan of Barry Lopez lately: Arctic Dreams (good stuff, ol Ed Abbey even liked this book), Of Men and Wolves, and I have Crossing Open Ground packed and ready for a trip this week.
Grizzly Years by Doug Peacock is a fun read.
Lots of good sailing books that anyone into UL hiking might also relate to. They range from The Cruising Life (a how to on ditching the 9 to 5 and going sailing) by Trefethren(?) to Adrift by Callahan (a survival story).
The Cormack McCarthy books are good and I think of All the Pretty Horses as an "outdoor book" to some degree.
That oughta hold ya for a few hours even if you got bumped on the flight.