A couple of games that have had surprising longevity in our house are Labyrinth and Apples to Apples, both of which my kids started on the Jr versions way back (and still use at 11 and 13), but also like the adult versions. Rush Hour is one with longevity and still makes the occasional appearance, too. (3D Hogwarts puzzles are our current new love, though!)
DS also fell in love with Munchkin at a D&D club several years ago (but screen for your tolerance for language, gore and general obnoxiousness). More recently, he's found Space Hulk at his school's games club.
However, his ultimate favourite remains Go.
