I think large scale space colonies, O'Neil colonies at GEO and beyond laregely build from near earth asteroid material is the way to go. 2 mile by 10 mile or so rotating cylinder. Earth normal inner outer edge gravity. Variable gravity toward the center. Solar mirrors for light and much of heat. Much better than being on some rock not at all fit for human habitation like the moon or Mars.
Of course first step is a doozy. IMHO we need lots of space robotics and nuclear space tugs to change down near earth asteroids to get it done. Can't do it with humans in space alone as we are fragile, especially outside van Allen belts, until a lot of supporting space infrastructure is in place.
