As I seem to be on a posting spree today, let me go one more.
There is an interesting post here about How to read books above your level.
I am unsure if I agree 100% with what the guy is saying, but I do know that the introduction is what propelled me through Dorian Gray (even if it isn’t that difficult) and it was worth every minute. I came out throughly depressed, but slightly awed, so it all balances out.
My simple advice is to read those more difficult books when you’ve got enough time on your hands to not be thinking about other things. Pretty darn obvious.