I've recommended Connie Willis'
To Say Nothing of the Dog in other threads, so I'll go with Ursula Le Guin's
The Lathe of Heaven.
(That's a sneaky way of getting in 2 recommendations)
http://www.sfsite.com/04a/lh173.htm
(I can't help it, but recently I've begun thinking of George Orr as George Orr Binks.)
