The Lost City of Z, David Grann. Engaging nonfiction about the author researching the life of Percy Fawcett, a Victorian explorer who ultimately vanished in the Amazon, and ended up looking for information about the guy's fate himself.
The Adventures of Sherlock Holmes, Sir Arthur Conan Doyle. Holmes is a classic for a reason, and the short stories are a lot of fun and easy to swallow. (There aren't any particularly bad collections of short stories, but if you want a Holmes novel, only The Hound of the Baskervilles is really worth it.)
The Sundering, Jacqueline Carey. Carey is more known for her Kushiel novels, which are all about geopolitical intrigue, romance, and sadists. They're great, but The Sundering—composed of Banewreaker and Godslayer—is much more accessible. It's a deconstruction of The Lord of the Rings which works by taking a similar situation making it morally complex.
The Magicians, Lev Grossman. Along the lines of the above, although this is a particularly brutal deconstruction of Harry Potter and The Chronicles of Narnia. It's also a trilogy, with the third book still in production.
The Unwritten. Ongoing Vertigo comic that's being pretty thoroughly collected. It starts as a deconstruction of Harry Potter (guess what I like to read!) and has become a meditation of how we interact with stories and they interact with us. In three years of reading it, there's only been one issue that stumbled for me, and that was recently.
A Fire Upon the Deep, Vernor Vinge. Brilliant classic sci-fi. To tell you anything more would be a disservice, but it flirts with the epic. There's a sequel, The Children of the Sky.
The Secret History, Donna Tartt. A novel about classics students committing a murder. The first half can be slow, but the second half is so amazing it barely matters.
Tigana, Guy Gavriel Kay. The novel that marks Kay leaving his Tolkien riffing behind and striking out on his own; it's about the efforts of a band of rebels to save their country, whose very name has been erased by the two dictators that vie for control of their continent.
Good Omens, Neil Gaiman and Terry Pratchett. A buddy comedy about the apocalypse. If you've not read it, you've probably heard of it.
Wicked, Gregory Maguire. While the other novels in the series don't match it, this is a very interesting character study, and I really like Maguire's Oz. (Which I say as if I even know about the original one.)
Zombie Spaceship Wasteland, Patton Oswalt. This is pretty evenly split between some brutal comedy that didn't work for me on the page and a darkly brilliant memoir. It's worth it for the memoir portions.
The Magician's Book, Laura Miller. Nonfiction about how stories influence us and the power of story by way of examining the author's relationship with The Chronicles of Narnia, as well as examining the life of C. S. Lewis.
Manhood for Amateurs, Michael Chabon. Pretty much everything he writes is worth it, but this is a nice collection of essays ranging from dealing with his children to a love letter to Big Barda.
That's just a random sprinkling. If you (or anyone else!) is interested in exploring on your own, librarian Nancy Pearl has two books—Book Lust and More Book Lust—that offer a lot of recommendations grouped by theme or topic. It's how my own towering reading list (now 500+!) got started.