Others that may appeal to young men (and young women, as well-- though the protagonists tend to be male):
Invisible Man or The Jungle, though both are probably more properly collegiate level than secondary.
Jack London's short stories (Call of the Wild for example).
Steinbeck-- which I am assured is an acquired taste. Of Mice and Men is a classic for a good reason, however.
Twain-- there is much to choose from there. Huck Finn would be the classic coming-of-age novel.
Ray Bradbury-- again, loads to choose from. Start with short stories, then move into Martian Chronicles or Something Wicked.
Lots of times, the "journey/quest" novel format is a metaphor and vehicle for a coming-of-age story.
