One peculiarity of this book, which I had forgotten, is that there don't seem to be any gay characters - which comes across as strange, given the wide range of character types. There is deliberate tension within the plot because everyone on the Mars Mission has been selected by the military-industrial-governmental system which they then come to resist once they get to Mars. It could therefore be argued that the state-run selection process has resulted in a biased sample. However, the issue as far as I can tell is never even discussed.
There is a pretty good overview of the characters of the Mars trilogy at wikipedia
and a wiki just about Kim Stanley Robinson's work here.