Hopefully after getting my VAT return sorted I will be able to contribute properly to this thread, as it is a subject very close to my heart.
For now, just a passing thought: in KSR's Mars trilogy, we see the surviving members of the original 100 grow to great age through the use of the "rejuvination" techniques discovered in Red Mars. However, their memories of their earlier times continue to fade as they age. I found this profoundly sad, and my initial excitement at the idea of such longevity was severely curtailed. As a young child I came to the conclusion that an experience unremembered is a tragedy, and I'm not sure I've really changed my mind on this...