First off, don't dismiss the older stuff that gets read by literature students. Most of it really isn't headache inducing highbrow 'serious' literature. People continue to read, for instance, Jane Austen or E.M. Forrester because they are very good writers.
I'd suggest going even further back into the annals of literary history. I first read Boccaccio's Decameron when I was around 16 and I absolutely loved it and, if you happen to like that, give Chaucer's Canturbury Tales a spin. Both books are not so much novels, in the modern sense, as they are collections of short stories strung together by a meta-narrative which provides the occasion for various characters to tell their stories. I guarantee you'll be surprised and delighted by their lewd humor and decidedly unpious character. The late medieval period was not nearly as stuffy as most people believe. In this same vein, you should also read Cervantes' Don Quixote.
Moving on, I'd highly recommend Diderot's Jaques the Fatalist. Like the Demcameron and Canturbury Tales it is a meta-narrative enveloping various characters personal stories, but it is more unitary and singular -- it is, properly speaking, a novel in the modern sense of the word. The personal reveries thematically relate to one another and contribute to the books central theme of free will and determinism. This is a wildly entertaining and profoundly thoughtful book by one the western world's most original and sophisticated minds.
Give Alexander Dumas a try. He is the great granddaddy of escapist fiction and his books are just plain fun. You might also give Balzac a whirl. His writing is simply fantastic -- if a little long winded -- and his great genius is an uncanny ability to create and depict an amazing psychological depth in his characters. I'd suggest his collection of short stories, The Droll Stories, as good place to start. And speaking of short stories, by all means, read the short stories of Chekhov and Edgar Allen Poe.
As for more modern stuff, pick up a copy of Hemmingway's collected short stories and if like them give one of his novels a try. I'd suggest For Whom the Bell Tolls, which is about the Spanish Civil War and is a profound meditation on the nature heroism and human savagery.
If you are at all interested in the period of English history between WWI and WWII read Evelyn Waugh's Brideshead Revisited, a coming of age story set in the era of a waning aristocratic culture.
Gabriel Garcia Marquez, a noble prize winner, is absolutely wonderful. A Hundred Years of Solitude and Love in the Time of Cholera are two of my favorite novels of all time.
I'd also suggest Milan Kundera. His later stuff is decidedly more 'intellectual' (while remaining very readable), but his earlier works such as The Joke, Life is Elsewhere, and The Farewell Party are more accessible and still very insightful. If you're at all interested in Eastern Europe during the Cold War era give Kundera a try.
I've found a lot of people who are into hard core science fiction (the stuff heavy on the science) really enjoy Umberto Eco. Eco's novels are incredibly dense and really manage to immerse you in a foreign world of ideas and culture. The Name of Rose manages to convey more about Medieval theology and the monastic life than most textbooks on the subject. Foucault's Pendulum does the same for world of hermetic mysticism and masonic conspiracies.
You might also give Salmon Rushdie a try. I've found that the first hundred pages of his books can be a little disorienting and you'll often find yourself wondering what in the world is going on, but if you persevere it all comes together and begins to make sense. Of all of his books The Moor's Last Sigh is my favorite.
Unity of mankind means: No escape for anyone anywhere. - Milan Kundera