Initial bases, first domed settlements, agriculture, towns, terraforming, and finally a new Earth.  How long will it take?  Inevitably, human problems will come with humans--is that reason for not doing it?  What are the forks in the roads?  What are the thresholds for self sufficiency, independence, and partnership with Earth.  How do assumptions about transportation and robotics factor into this?  There are likely many answers, but what are the interesting ones?