Interesting to compare Harriet the Spy and Scout from To Kill a Mockingbird. As a kid growing up when these books were first published, I was always attracted to interesting female characters. There was no shortage of them. One of my favourite Narnia books was The Silver Chair. The other three kids were now too old to go to Narnia, leaving Lucy to have all the adventures. There was no shortage of books about girls doing ungirllike things. Pippi Longstocking comes to mind. Maybe Anne of Green Gables and Pollyanna were more girlly, but for some reason I never read those. I like my girl characters adventurous and bad.
Lucy wasn't in the Silver Chair! You probably mean [EDIT: Voyage of the Dawn Treader, rather], which was definitely my favorite for that reason. Lucy was a more interesting character than Peter. Silver Chair did have a great female character. CS Lewis knew how to write children in cool ways.
You're right. It was Jill and Eustace that went off to Narnia - but Eustace seemed kind of useless and Jill saved the day. (Maybe, it's been a while.) Peter wasn't in The Voyage of the Dawn Trader. It was Lucy's brother Edmund, no? Edmund who screwed things up badly in the Lion, the W and the W. -- and it was Lucy who found Narnia in the first place. Lucy: you go girl! As a kid, I spent a lot of time thinking about the world between worlds where some of the action of The Magician's Nephew took place. And now here we are in Hubski, a world between worlds.... or maybe Google is the world between worlds, where you can jump into any lake and emerge in a new world....