Must be some other women they're talking about.
Does she like philosophy? I'd suggest C.J. Cherryh's
Wave Without A Shore. Orson Scott Card's
Songmaster might also be a good choice. If she likes politics, Frank Herbert's original
Dune is a classic. I think Heinlein is a little heavy on science and engineering for someone who doesn't like those subjects, though he has great characters and tells a ripping good story. His "Young Adult" books, e.g.
Have Spacesuit, Will Travel are quite good. Um... Arther C. Clark's
Dolphin Island is very readable, and rather less on science than characterization.
It would help to know what else she likes to read. I could make better recommendations, then.
Edit: Somehow I missed seeing that this discussion went on for 4 pages before I posted. Knowing that she liked
Ender's Game, I would recommend John Barnes'
Orbital Resonance and probably Ian Banks'
The Player of Games. I also highly recommend Card's
Speaker for the Dead (I didn't think the books after that were quite as good) and probably
Ender's Shadow, which tells a story overlapping the time period of Ender's Game, but from the point of view of Bean, one of the other characters. I liked the sequels, but others have given them mixed reviews.