Everybody will sit throughout the show, so seeing won't be a problem.
Dude in front of me at the Dallas show had his 3 girls with him. Seemed to me about 10-12-14 or something like that. Youngest one had a great time. Helped that she was clearly a fan (they all knew all the words). I gathered it was her first show, too. Afterward, when everybody was standing to cheer, he put her up on his shoulders and took her up front so they could all slap hands and whatnot. She was pretty damned excited about it, and the band seems to enjoy seeing them out there (which I've noticed at a few shows).
I'd say that if she digs the music she'll have a blast. If not, she'll probably still have a good time, but in a different sort of way.