Sorry to be stubborn, but read the sci-fi novels of Iain M. Banks. You don't crave for others after reading them...
(And yes, you are frustrated when he does not write a sci-fi novel in a year X...)
Unimaginable fantasy, incredible characters, especially female (that confessed also by my female-feminist friends who dig the books wholeheartedly), never really know what's going on and the worlds are just astoninshing!