(Continuing from the comments/discussion following an earlier post ...)
Generation starships: they're not fast.
If you can crank yourself up to 1% of light-speed, alpha centauri is more than four and a half centuries away at cruising speed. To put it in perspective, that's the same span of time that separates us from the Conquistadores and the Reformation; it's twice the lifespan of the United States of America.
We humans are really bad at designing institutions that outlast the life expectancy of a single human being. The average democratically elected administration lasts 3-8 years; public corporations last 30 years; the Leninist project lasted 70 years (and went off the rails after a decade). The Catholic Church, the Japanese monarchy, and a few other institutions have lasted more than a millennium, but they're all almost unrecognizably different.
Consumer capitalism along our current model simply won't work as a way of running a long-duration generation ship (the failure modes are lethal and non-recoverable). Communism (or rather, Leninism) has a slightly better prospect, but is still a long way from optimal. Monarchism is just a pretty word for "hereditary dictatorship supported by military caste". What are the alternatives? And what do we need to consider when designing a society that can survive for a 500-1000 year voyage in a bottle without exploding? (I'm assuming, for the sake of argument, that suspended animation or life extension technologies don't change the picture out of all recognition; after all, even if you can expect to be alive in a thousand year's time when you reach Barnard's Star, you're not going to get on the ship in the first place if the living conditions are intolerable.)
Designing a space habitat/generation ship with the implicit parameter that the crew are expected to work 40-60 hours a week is a really bad idea; efficiency is the enemy of redundancy, and multiple redundancy (in life support and propulsion) is absolutely vital to any such project (because it provides resiliency that is essential to have any hope of recovering from a disaster). What if the population crashes? If you've designed your ship to require a 40-hour work week by 1000 maintenance crew and you're down to 250 crew, you're going to die. A 10-hour work week, in contrast, gives them a fighting chance of survival in event of a major die-off.
A sensibly designed long-duration hab would require the crew to do just enough work to maintain the necessary skill set (you don't want them to go rusty), but leave lots of time available for education, recreation, and socialisation. You can't build a stable hab culture on material acquisition because it has to function in a resource-bounded environment (although soft goods/intellectual property is another matter, if you want to provide an escape valve for acquisitive urges, or a "training wheels" environment for the market-mediated culture that you might need to revive after arriving in another solar system).
I've been (inconclusively) batting around some ideas with Karl Schroeder — how do you design a society for the really long term? There are a couple of levels to consider: notably, decision-making and economics. And it doesn't look as if we've got any good solutions to either.
Administration first: Democracy is prone to mutation into some other form (kakistocracy, oligarchy, populist dictatorship). Monarchy has a single point of failure and historically only worked when there was a draconian enforcement regime backed up by Malthusian pressure (whenever the lid came off — e.g. with the opening of a new frontier for emigration — the oppressed tended to vote with their feet: aboard a generation ship, their only option would be to vote with the knife). We were somewhat intrigued by the idea of a society with multiple designed-in local attractors, so that over time it can oscillate between different modes of governance (but returning eventually to previous patterns); but nobody's tried it yet.
Another issue to consider is the need for designed-in escape valves. The social pressure on a generation ship is going to be fierce; but if there's a designed-in expectation that, say, 20-50% of the inhabitants at any given time will be preoccupied by non-functional distractions such as the arts or sports, that might go some way to defusing social stresses. Arts and sports can act as vectors for social competition and status-seeking, while being channeled easily in directions that don't consume excessive physical resources.
One thing I'm pretty certain of is that the protestant work ethic underlying American-style capitalism, with its added dog-eat-dog ethos, would be a recipe for disaster aboard a generation ship — regardless of whether it's run as a democracy or a dictatorship. American (or British) working hours are a bizarre cultural aberration — and a very local one. More to the point, competitive capitalism tends to reward increases in operational efficiency, but efficiency is most easily optimized by paring away at the margins — a long-term lethal threat to life in this situation. The "tragedy of the commons" has got to be engineered out aboard a generation ship, otherwise the residents will wake up one [virtual] morning to discover someone's acquired a monopoly on the oxygen supply. And that's just for starters.
(Finally, don't get me started on libertarianism. Economic libertarianism -- in the contemporary American sense -- aboard a generation ship would be just plain suicidal. It's dog-eat-dog capitalism with the brakes off; I'm of the opinion that libertarian ideology is based on a falacious theory of mind, and would in practice degenerate rapidly into a rather nasty form of industrial feudalism. The end point of which is monarchism, and bloody handed revolution. Not the kind of metastable multiple-attractor society I have in mind at all ...!)
So. You, and a quarter of a million other folks, have embarked on a 1000-year voyage aboard a hollowed-out asteroid. What sort of governance and society do you think would be most comfortable, not to mention likely to survive the trip without civil war, famine, and reigns of terror? (NB: communication with the home world is assumed, as is the ability to implement any innovations they come up with that don't require a work force greater than 10% of your people.)