What is a good science fiction book?
Orson Scott Card: Ender's Game (and the rest of that series)
Frank Herbert: Dune
Anne McCaffrey: The Pern series (many people think this is fantasy because of the dragons, but if you read the books that are chronologically earlier in the series, you will find that they are genetically engineered lizards). Many of the books in this series appeal to all ages.
Robert A. Heinlein: "Orphans Of The Sky," "The Puppet Masters," "Citizen Of The Galaxy," "Glory Road," "Tunnel In The Sky," and "The Man Who Sold The Moon" (although some of these may be a little dated, they're still a great read).
Andre Norton: The Time Traders series, The Solar Queen series, The Beast Master series, "Star Rangers" and "Star Guard."
Isaac Asimov: The Foundation Trilogy ("Foundation," "Foundation and Empire," and "Second Foundation"), The Robots Trilogy ("I, Robot," "The Caves Of Steel," ...more