This brings back some memories... Where the Wild Things Are, The Very Hungry Caterpillar, The Cat in the Hat...
For "early teens"... The Call of the Wild (excellent book), The Outsiders (good movie; never read the book), The Hound of the Baskervilles, The Hobbit...
If I had kids, I'd start them reading from the list NOW.
100 books every child should read - An introduction by Michael Morpurgo - Telegraph