I prefer the Oort cloud colonization plan. Since Oort clouds stretch so far out they touch between the stars.

Once the problem of living on a comet has been solved, you get something like the Polynesian islanders. People would move from one commet to the next. One generation at a time, for more living space and more resources.

I wonder what people in a generation ship would do when they arrive at a star and discover the comets of the star system are already inhabited.