A relatively obscure book: Ransom, by David Malouf, which is a rewriting of the last parts of the Iliad - specifically, the events of the Trojan king, Priam, travelling to Achilles to buy his son's body from him, and give him a proper burial. It's a plot I wish I came up with first and darn you Homer, you sneaky git.
It is easily my favourite fantasy (if, er, that's correct to call it?) story of all time. It's as beautiful as I remember having read it (read it for school, in fact, as a set text!) and even better, being that I understand the whole thing more clearly.
It is a sad, brilliant story, and it all goes into exploring the relationship of death and life, and of mortality and what being mortal means, and so on and so forth.
Achilles and Priam are both greatly detailed characters - broken, flawed men, in different ways, but ultimately more similar than either of them realise. It has such a bleak tone and feel and conclusion, but, at the same time, is incredibly uplifting, as it were. It's one of the only fantasy stories I've read that's touched me, in that sort of manner.
Also, it is a tiny book. Only 200 or so pages.
And for poems, I am deeply in love with the works of Coleridge, and also T.S. Eliot. I recommend the Rime of the Ancient Mariner, which feels like a fantasy story before everyone started ripping off Tolkien, and Kubla Khan, which feels just as surreal and fantastical, if a lot shorter and easier to ingest.
T.S. Eliot took me a bit to get into but, man, is he brilliant. I consider his Preludes to be some good stuff - it's basically just a series of descriptions of scenes in a city, but he creates such a fantastic mood and tone and symbolism with it. It's some of the best descriptive prose I've seen, and it's not even a prose story!
The Lovesong of Alfred J. Prufrock and The Hollow Men are similar.
It's all pretty bleak though so, iunno, maybe play Kirby or some such after reading it.