Wrinkle is an all-time great, in my opinion. If I remember correctly, the three mystical ladies are Stars, right? Has anyone ever read another book that characterizes Stars?
It's a pretty minor part of the book, but C.S. Lewis's
Voyage of the Dawn Treader includes a character that was formerly a star.
I loved her work. Of course, I only managed to read and enjoy the first two in the series. For some reason A Swiftly Tilting Planet never quite grabbed me.
I had a really hard time getting into ASTP as a kid, despite loving AWIT, but when I read it later as a teen I enjoyed it very much.