You probably know a great many of the authors I love from Charles Dickens, Jane Austen, Oscar Wilde, the Bronte sisters and more through the classic children's authors like Louisa May Alcott, Lucy Maud Montgomery and Frances Hodgson Burnett.
Instead of making a detailed list of them, I'll name two books I bought a few years ago because they sounded so interesting to me - but have yet to read. They are both mysteries/thrillers.
-Duplicate Keys by Jane Smiley (Amazon's description: "Alice Ellis is a Midwestern refugee living in Manhattan. Still recovering from a painful divorce, she depends on the companionship and camaraderie of tightly knit circle of friends. At the center of this circle is a rock band struggling to navigate New York’s erratic music scene, and an apartment/practice space with approximately fifty key-holders. One sunny day, Alice enters the apartment and finds two of the band members shot dead. As the double-murder sends waves of shock through their lives, this group of friends begins to unravel, and dangerous secrets are revealed one by one. When Alice begins to notice things amiss in her own apartment, the tension breaks out as it occurs to her that she is not the only person with a key, and she may not get a chance to change the locks." see http://www.amazon.com/Duplicate-Keys-Jane-Smiley/dp/1400076021/ref=sr_1_1?ie=UTF8&s=books&qid=1231367311&sr=1-1 )
-The Eight by Katherine Neville (Amazon's description: "Katherine Neville's debut novel is a postmodern thriller set in 1972 ... and 1790. In the 20th century, Catherine Velis is a computer expert with a flair for music, painting, and chess who, on her way to Algeria at the behest of the accounting firm where she is employed, is invited to take a mysterious moonlighting assignment: recover the pieces of an old chess set missing for centuries.
"In the midst of the French Revolution, a young novice discovers that her abbey is the hiding place of a chess set, once owned by the great Charlemagne, which allows those who play it to tap into incredible powers beyond the imagination. She eventually comes into contact with the major historical figures of the day, from Robespierre to Napoleon, each of whom has an agenda.
"The Eight is a non-stop ride that recalls the swashbuckling adventures of Indiana Jones as well as the historical puzzles of Umberto Eco which, since its first publication in 1988, has gone on to acquire a substantial cult following." see http://www.amazon.com/Eight-Katherine-Neville/dp/0345419081/ref=sr_1_1?ie=UTF8&s=books&qid=1231367788&sr=1-1 or http://en.wikipedia.org/wiki/The_Eight_(novel) )
I've heard this one referred to as having some fantasy, but it appeared to me more like a puzzle which spans a few centuries, one century meshing with another.
If you enjoy reading plays and haven't read them, I would recommend Cyrano de Bergerac by Edmond Rostand and Pygmalion by George Bernard Shaw (among many other greats).
B.Q. I don't read much poetry, I must admit, so I don't have a single favorite. I do like The Lay of the Last Minstrel, Canto Sixth, I by Sir Walter Scott: http://www.theotherpages.org/poems/canto06.html
I suppose this isn't precisely what you wanted, but narrowing it down is tough, and I don't want to repeat the same classic titles (which you know, anyway).
***Note: I'd agree with Dix about Nero Wolfe; they are really good ones, and, like Dix, I love Archie. You might enjoy Dorothy L. Sayers' Lord Peter Wimsey series of mysteries (Whose Body? being #1), too. I like some of the other book suggestions, as well, especially Azriel's and Blue Coral's suggestion about Mary Stewart.
***Dix, The Rule of Four looks interesting. I put it in my Amazon wishlist. :)