Hi Jen! Hey, thanks for that suggestion. I have really found it subversively fun to share my young reading likes with my niece. All that part of the family is pretty sure I'm not a good influence on kids, but it's *so* delightful to turn this little gal onto some thinking girls books.
It's really been nice because this niece has had lots of troubles with some learning disabilities and the school has pretty much labeled her as somebody "not smart." She'd be a perfect candidate for home schooling but her parents are afraid to try. It did my heart lots of good to hear her so jazzed over Citizen of the Galaxy. You or Rose should have been there to hear her! She's grokked Heinlein. :-)
Let's see. If she likes that one - well, she has good taste! I recommend "Tunnel in the Sky", "The Rolling Stones" "Podkayne of Mars", "Double Star" (a good lead-up for Moon is a Harsh Mistress) and if you're being really subversive, "The Door into Summer".
Sigh. I was lucky to have a dad with good taste when I was 12 and star-struck. Sounds like your niece is lucky to have you around.
Star Beast is also great ... loved Lummox!
And, WN, I think your niece would like Have Spacesuit ... PeeWee and Mother Thing always make my day! And wouldn't you love to have a man like Kip around the house? That's a man worth having!
I think it's important for girls to read Heinlein, to see what kind of men are worth associating with.