Well I think colonies are one of the next logical steps to take when you think of the commercial aspects to space, and trying to draw the average citizens' interest. Tourists need places to go after all. Then with any luck, the costs in flying people to and from those places will help pay for the spacecraft services that bring them, but perhaps even pay for the sustainment of those colonies to some extent.

Exotic locations attract tourists, tourism attracts companies/corporations, corporations attract more tourists, more tourists attract settlers, settlers...well, you know.

 

The point is, space colonies would probably start off as tourist locations and slowly, but surely attract more and more people, until finally people don't want to leave and start living there. I can see space colonies as being one the first steps toward "living among the stars" because of both the awe and fun of it, and the economic gain there it would possess.

Mars I do not exclude, though, because humans are, by nature, curious and what wouldn't quench our thirst for exploration into the unknown than to set off and land on a planet that is not Earth....

Here's the info on the Plasma Rockets for the mission to Mars.

The Top Three Reasons to colonize Space