Would also highly recommend Finding Sky by Joss Stirling, the first in the Benedict Brothers/Soulfinder series.. Fun, exciting, romance, action, what more can a girl need?!
The Boy in the Striped Pyjamas is a wonderful book and definitely age appropriate, but it may get the usual teenage response (that I got from Charlie) that it is boring as it's not current day.. He really enjoyed The Curious Incident of the Dog in the Night Time though..