The Farthest Shore by Ursula K. Le Guin

This novel, the third in the Earthsea cycle, offers an ending to the first three books. It's about the line between death and life, and the necessity of death to make life meaningful. It's also a coming-of-age story, as Arren grows into his kingly self. Le Guin takes the story as far as it needs to go and doesn't waste a lot of time wrapping it up or writing epilogues (although she has written three Earthsea books since this one ended the trilogy).