I agree with you that reading is most enjoyable when it is the source of learning and gaining knowledge. I read many more non-fiction books in fact. Still, a good fictional book can be a valuable source of information when considered in a different way.
Would you say that a Shakespeare play, Julius Caesar, contains valuable information that may aid you in your daily life?
Classics are a very different kind of book. Shakespeare works, even the comedies, are filled with insights about the human being, but, due to their distance in time, they don't worry me much about rights or wrongs. The same could be said about, for instance, Don Quixote by Cervantes or The Iliad by Homer.
Precisely. As you say classics can provide timeless insights. In my opinion, Infinite Jest is a modern masterpiece. Of course, time will tell if it becomes a classic.