I've just finished Hamilton's Commonwealth Saga and it's definitely one of the best books I've read in a long time. The first three Dune novels are particularly good. Dune has a tendency to get more philosophical in the later volumes (plans within plans within plans). If I had to choose an all time favorite I would probably go with Kim Stanley Robinson's Mars trilogy (Red/Green/Blue Mars). An extremely well researched view of how Mars colonization and terraforming might proceed in a realistic way. He also has a trilogy on the possible/likely consequences of runaway global warming (Forty Signs of Rain, Fifty Degrees Below, Sixty Days and Counting) but RGB Mars is definitely better. Edit: "The content of Green Mars and the cover artwork for Red Mars are included on the Phoenix DVD, carried onboard Phoenix, a NASA lander that successfully touched down on Mars in May 2008. The First Interplanetary Library is intended to be a sort of time capsule for future Mars explorers and colonists." http://en.wikipedia.org/wiki/Mars_trilogy#On_Phoenix_spacecr... (http://en.wikipedia.org/wiki/Mars_trilogy#On_Phoenix_spacecraft)
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