I am still listening to Red Mars on audio. What an achievement it is. Coming back to it after fifteen years or so I am struck by how well written it is. Also how well it fits into the modern world, and how its themes have stayed with me personally. This may be what got me interested in Jungian personality theory, for instance, and I can see how much of my private writing has been influenced by KSR's way with imagery, in particular the imagery of stone. Coming back to it again I can see through the heavy detail of each scene to understand the overall structure of the book better. Key figure decides to become 'the first detective on Mars' at almost exactly the half way point, for instance, and solves the case at the start of the final act. I think when I read it in the early to mid nineties I thought all SF would be like this from now on, with fully developed characters, a good range of ethnicities, women (including older women) taking an active role alongside the male characters, just like in real life. I don't think the books I have read since have lived up to this expectation (with some beloved exceptions).
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.