The gnawing, intractable loss of genetic diversity in a spaceship ecosystem made for an interesting conflict source.

Reading Diaspora right now from a rec on hn and just loving the intentional handling of conflict in that as well.

Well of course not, but building colonies inside the solar system is much more forgiving. In fact much of the potential benefit lies precisely in trade between Earth and the colonies.

Maybe there can be some of the advantages of a system sent along. A multigenerational fleet with multiple ships, capable of trading among them, but also providing a degree of separation and differentiation. You could even try attaching some engines to asteroids and comets full of useful materials to send along side the fleet, ready to be used if the self sufficient systems fail, and for the colony when they finally arrive.

Another good point from Kim Stanely Robinson is 2312's constructing habitats from hollowed out asteroids. Way easier than refining and moving so many tons for steel to build a habitat from scratch.

I also love the ecological designing of each habitat -- whether to go with recreating a (likely lost) natural habitat or to create a new "Ascension".