My wife enjoys reading. Over the past couple years she has really gotten into reading novels and most of these come recommended by her sisters. I'd really like her to break into the world of science fiction fantasy, but I'm not sure where to start.

I'm trying to tread lightly and not turn her off of the entire genre, and I was wondering if anyone had any suggestions to recommend to her?

She mainly enjoys more mainstream novels and authors:

Barbara Kingsolver
The Time-Traveller's Wife (kind of sci fi/romance) by Audrey Niffenegger
Into the Forest by Jean Hegland
The Secret Life of Bees by Sue Monk Kidd

On the flip-side, we listened to an audio version of Ender's Game a couple years ago, and she really didn't like it at all. (buggers!)

Any ideas?