I read Don Quixote in school, but it's been a long time. In my mind, the "canon" version is now Man of La Mancha which, as the article notes, "could not be more distant" from the original. I find the same has happened with The Secret Garden and The Scarlet Pimpernel.

I'm not immediately convinced that Don Quixote is a more effective manual for living than other classic works of literature, but it's interesting enough to make me consider a reread. I'm sure it would be a completely new experience.