We were discussing these on the other thread, and someone called Cormac McCarthy's "Border Trilogy" a quest novel, but it's really not. It's Literature, big L. Try it, you'll never be the same.
All the Pretty Horses
City of the Plain = trilogy.
But it is still a 'quest' type novel. Young hero on a search for something, self or treasure or whatever, strikes out into unknown lands,etc.
Pretty Horses is a masterpiece.