I read Gone with the Wind at twelve...if she's a big reader, she might be into it now!
If you want something less intense/thick, you could try the Little House series by Laura Ingalls Wilder. I'm going to get a nice set for Dagmar before we leave, hopefully in a few years she'll want to read them. Especially since they detail a piece of American history, it might be fun/interesting for her.
Also, Maud Hart Lovelace's []i]Betsy/Tacy[/i] stories..there's a series of them, and they also chronicle American turn-of-the-century small town life (you may want to read these first, though, because if I remember correctly there is a Christian influence-at least I remember one chapter where they talk about God. I don't recall them being really Christian in nature, but I do remember that scene.)
Oh, and the Great Brain books-can't remember now who wrote them. But I really enjoyed them and thought they were fun.
I will keep thinking...
Hmmm...what else...