Probably not what you had in mind, but I found Neal Stephenson's novel Seveneves to be very thought provoking on the subject. I had never thought of inflatables before I read that.

I can recommend Gerard O'Neill's The High Frontier. https://www.scribd.com/doc/239652061/The-High-Frontier-Human...

Thanks for the recommendation for The Millenium Project, jasonpeacock, I'll check it out. :-)

This is an older, but very practical and educational read: http://smile.amazon.com/Millennial-Project-Colonizing-Galaxy...