I was just trying to think of things that I used to watch/read/play with and whether or not I'd like to see adaptations of them hit the movies:
Sailor Moon - No, I just don't think it would work.
Babysitters Club - No, I've grown up enough that I'm not really interested in them any more.
Barbies - Uh... I don't think so. I remembered the thing I liked about Barbie was that I could make my own stories and act them out using the dolls, watching a movie about them wouldn't be the same.
Nancy Drew - Maybe. I know this was already remade, but it was aimed at a young audience, and they didn't even try to entice us with the nostalgia value. If they made Nancy older, and made the story mature enough that someone my age would actually find it interesting, then I think it could actually work.
Other than that I don't recall being that girly when I was young - my favourite toys were Lego, my favourite books were the Animorphs series and my favourite film Star Wars: A New Hope.
One thing I might like to see though, would be a superhero film starring a heroine, like Carol Danvers for example. Especially if it was aimed at women instead of, or as well as men. It'd be difficult for it to stay out of cliche territory, but I'd really like to see what they do. Personally I think it's a bit sad for an amazing actress like Natalie Portman to be languishing as a love interest in a superhero film, when I'd much rather see her starring in one. And don't take this as a suggestion to make a Black Widow film starring Scarlett Johansen, she was one of the reasons I didn't bother seeing Iron Man 2.
One thing that I think is a problem with things aimed at young girls is the fact that what we were often exposed to is not something that we grow up and continue to admire. Take the Disney movies for example. I use to love them as a kid, and although I still love them now, when I rewatch them I take them with a pinch of salt. For example I no longer think it's romantic that Ariel was willing to undergo a drastic, and no doubt painful, physical change to meet a man that she'd never spoken to, so she could get married at sixteen. The Disney ladies I do still like are Mulan, Jasmine from Aladdin and Megara from Hercules.