There are a few suggestions above which make me want to scream!
However bright a 12� year old might be, he's still only just getting to grips with his own sexuality. How on earth can he be expected to understand the sexual ambivalence of Lolita?
I'd also suggest that the deeper meanings within Lord of the Flies are beyond the understanding of most youngsters of that age. (The same also applies to Animal Farm. They were both set texts when I was at school, but I wish they hadn't been. They're much easier to understand, and to enjoy, from an adult perspective).
Irrespective of the titles chosen, the key message to impart to any young person is that books are there to be enjoyed, not simply studied. (Leave that to university professors!). 'Enjoyment' isn't a word which many youngsters would genuinely associate with most of the books listed above. (I've yet to find any adult who's really enjoyed anything by V S Naipul, yet alone a child! I'd rather read a phone directory!)
Thank heavens for some 'fun' reads listed above. (Good literature doesn't have to be 'serious'). P G Wodehouse certainly gets my vote. I'd also like to add the funniest book in the history of the English Language: Jerome K Jerome's Three Men in a Boat.
Thank heavens, as well, for a bit of excitement in some of those suggestions. Mark Twain, Conan Doyle and H G Wells also get my support.
And where's the poetry? (Yes, I know you asked for novels but poetry is at least, if not more, important when you're seeking great English literature). John Betjeman is easily accessible, as is John Masefield. Rupert Brooke's work provides a good link with history. Philip Larkin and Benjamin Zephaniah should also be in the list.
Chris