Hands down, my favorite books for most of elementary school were The Baby Sitter's Club. Who else?
My sister just gifted me a revamped BSC (because that's what all the cool kids called it) graphic novel, by Raina Telgemeier. The graphic novels combine story lines from multiple books and reading one was a fun way to revisit my childhood. I also surprised myself with how much I remembered of the stories! Never mind that I seem to have forgotten half of the basic math I learned during 4th grade, it seems my brain decided to retain the names of all seven Pike children instead.
If you really want a throwback...
"What Your favorite Babysitters's Club Member Says About You"
Remember the TV show? How about the movie?
Also, Kirsten Dunst was on a book cover!