So many wonderful pieces of literature, enjoyable and beneficial.
Some of my favourites would be George Orwell - 1984 (a little bleak), the Discworld novels of Terry Pratchett (well written and amusing), and the superb horror books of James Herbert spring to mind.
Tastes, of course, can vary, but quality will always rise to the top. The Grapes & War and Peace are well written, but just think how many other superb books you could read during the time it takes to read each one of those mightty tomes! Then again, there is a lot to be said for quality over quantity:)