In my opinion, Nancy Kress ranks among the best visionaries of the future, as original and philosophical as John Varley, without the outrageousness. She obviously has an excellent grasp of socio-political history and trends, which she uses to build a convincing and complete future society.
The book starts in the near future, 2008. Genetically modifying children is commonplace, and for rich entrepreneur Roger Camden, his daughter will get the best of what's available - including a new, experimental genemod for Sleeplessness. Leisha Camden, like the 19 others before her and the thousands after, is extraordinarily intelligent, cheerful, talented, and for all intents and purposes, immortal. Her unmodified twin sister, Alice, is a Sleeper, and the rift between them mirrors society's distrust, envy, and eventual hatred of the Sleepless.
To escape this hatred, another Sleepless, Jennifer Sharifi, creates Sanctuary, an orbital community of Sleepless. Separate from Earth, but still tied to it, Jennifer's obsession with Sleepless superiority and their liberation from the Sleeper "beggars" goads her into progressively more radical actions. Only Leisha resists her, remaining on Earth with her mixed Sleeper and Sleepless family.
Sprinkled with the perfect mix of science, history, economics, and politics, with an original and thought-provoking storyline.