Cities in Flight deals with long-term space travel. The cities are actual Earth cities (like New York and Scranton, Pa.) that were able to literally pick up and leave the planet thanks to the development of the spindizzy. Some of the city inhabitants were able to live effectively forever, thanks to drugs that were available; but only if they had the skills needed by the city. The City Fathers tutored the children of the city, decided who would be a citizen with skills that were needed (and live forever with geriatric drugs) and who would be a passenger with a normal life span.
It's easy to think that because the City Fathers are dead, they're also stupid… Otherwise they would never be given the power they wield - and in some departments their power is absolute.
Suppose they had a breakdown?
If there were only a few of them, that would be a real danger; but there are more than a hundred, and they monitor and repair each other, so in fact it will never happen. Sanity and logic is their stock in trade.
From Cities in Flight, by James Blish.
Published by Avon in 1957.

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