Just as an aside, my daughter is 7 and in second grade and she and most of her friends have already outgrown Junie B and are on their way out of Magic Treehouse. A 9 year old (especially if she is an avid reader) may find those books too young for them.
Yeah, I was gonna say. Junie B. Jones is WAY young for a 9-year-old. I would have been reading those books in kindergarten - but I wouldn't go by my reading level, because I was reading in 2 languages by the age of 4 and at a college level by the age of 9.
I wouldn't recommend "Are You There, God? It's Me, Margaret" for a girl of 9 - it's a bit more "mature" (albeit dated) than she might be able to handle. At age 9, I could read the book well enough, but the subject matter would have been way beyond my grasp. I'd stick with more kid-friendly Judy Blume titles - "Blubber," "Tales of a Fourth Grade Nothing" (and the whole rest of the Fudge series), and "Otherwise Known as Sheila the Great."
As far as I can recall, even though the books were a bit below my reading level, I still enjoyed Beverly Cleary, particularly Ramona and the Henry Huggins books, at that age. I worked my way painstakingly through every single volume of the Little House books, fiction and nonfiction, including a biography of the real Laura Ingalls Wilder, which is very different from the account of life given in her books, though no less interesting.
I remember reading (and really loving) "The Lion, the Witch and the Wardrobe," "The Phantom Tollbooth," "The Borrowers," "The Witch of Blackbird Pond," "Island of the Blue Dolphins" and "Bedknobs and Broomsticks." I also loved the "Mrs. Piggle-Wiggle" series by Betty McDonald, although I'm not sure how easy those books would be to find these days. Other favorites were "The Egypt Game" by Zilpha Keatley Snyder, the "Anastasia Krupnik" series by Lois Lowry, and the very oddball "Jennifer, Hecate, Macbeth, William McKinley, and Me, Elizabeth," by E.L. Konigsburg, as well as a fairly creepy book which I'm not sure is in print anymore, called "Behind the Attic Wall" (not sure of the author) and "The Indian in the Cupboard," by Lynne Reid Banks.
A lot of the books I've mentioned are really, really dated, but hopefully she'd devour them anyway. I did.