A book that I love also addresses the metaphysical, Haruki Murakami's 1Q84. It's fiction, but also an extraordinarily entertaining read. Most of Murakami's books and stories touch on the metaphysical, but this one is more clear-cut and accessible than his other novels, I think (although it still has dead ends, including an antithesis to Chekhov's gun). The book is a monster though, so you trade clarity for sheer volume.
A shorter read that also deals with a metaphysical sort of reality or dreamscape by Murakami is Hard Boiled Wonderland and The End of the World. It's two novels in one. All the odd chapters are Hard Boiled Wonderland and the even chapters are The End of the World. I recommend read through all the odd ones first. Then go through and read the even chapters. Hard Boiled Wonder land is a sort of cyberpunk novel and the end of the world is kind of a fantasy story or dream like story that's kind of hard to explain. It is an absolutely fascinating book, and it was my first exposure to Murakami. I've read a couple of more since then (Wind Up Bird Chronicle and After Dark).