Reading the "Classics"

Since becoming a librarian eight years ago, one thing that has become clear is that there is a gap in my reading.
I was in elementary school through the 70's and early 80's.  I read a ton growing up at that time:  Nancy Drew, Little House series, etc.  In 7th grade I started Sweet Valley High and series such as that.  While I read a lot of books that would now be considered "classics" there are a lot I didn't read.  (I didn't even read A Wrinkle in Time until I was in my 30's!)
This year one of my challenges will be to read twelve such classics, to get myself caught up.

I am starting with Homecoming by Cynthia Voigt.

I have a few others on my list, but I need help.  What do you feel is considered a classic middle grade/young adult book?  What was one you remember reading when you were young that you loved?  I need some ideas!

Edit:  I wrote the above before I went back to school from break.  At first I was going to only read things from the late 80's and 90's which were the years I would've missed out reading some of the classics from (due to high school and college).   But, I found a few that I know I need to read that were from the early 00's, which makes sense because I was having kids and teaching kindergarten so I would've missed those as well.