Some Great Slightly-More-Modern Options (that alas aren't available on Audiobook)

Holes by Louis Sachar

The Twelfth Day of July by Joan Lingard

The Secret of Platform 13 by Eva Ibbotson

The Scarecrows by Robert Westall

The Machine Gunners by Robert Westall

Forever by Judy Blume

The Alanna Chronicles by Tamora Pierce

Why the Whales Came by Michael Morpurgo

Knight Crusader by Ronald Welch

Okay I admit they aren't very modern but I have very high standards so it takes many years for a new book to make it onto my list!

Your local bookshop will also have plenty of good suggestions - don't just read the latest bestseller; get some advice.