Thanks for additional suggestions! I thought about Life of Pi. She has a philosophical bent, though she's pretty ignorant about religion. She's also become interested in historical fiction. She has never liked mysteries (must be genetic--I don't care for them either), but I think she might like Wodehouse. She does not like war/military/violence themes, and I think is not too interested in full-on love themes (even if chaste), but light romance is probably okay. She is reading Little Women right now and enjoying it greatly.
Part of the reason for my question, btw, is that our choice of schools means that English/LA is not a strength. We knew this, but it's a shame, so I want to enrich outside of school. I'm willing to co-read and discuss, and she's into this idea. We did this a little this summer with Bradbury.
I would say she is obviously a strong reader, but not phenomenally strong. For some reason which I have never understood, her vocabulary lags behind what I would expect from her. (She has a Kindle now, which should help, except that I don't think she likes to use the dictionary feature.) However, I am always impressed with her thematic understanding. Vocab-wise, I wouldn't put her higher than 9th grade level. That puts plenty of adult books in reach, though.
