Kathy,
National Treasure is a little intense at times, so I am not sure how your 9-year-old will like it. My DS-10 gets scared sometimes during movies, but he liked this one a lot.
Like I said in my earlier post, I think this movie is geared more toward adults and older kids. Even though is it is a Disney movie, it is not a "kid's" movie. I guess you can compare it to Pirates of the Caribbean. If your DD handled that movie okay, she should be fine with National Treasure.
I hope that helps.
Gayl