http://en.wikipedia.org/wiki/Mars_trilogy
The first book, Red Mars, follows the colonization from an initial expedition of 100 scientists to the building of a space elevator and the development of an independent culture.
It's a good mix of hard science, politics, and the interpersonal relationships of the original 100 colonists.
The only technological assumption I thought was a bit of a stretch is independent robotic machinery. They can use these to perform public-works scale construction or filter minerals out of the dust with little human input.
Bad, bad book.
I found this book horrifically tedious, and everyone I talk to apparently thinks it's the Greatest Story Evvvaaaarrr1!!!11!! It's nice to know that I'm not completely alone on this.
All that said Red Mars is essential the canonical book when it comes to Mars colonization. Some excellent ideas are imaginatively explored within.
http://en.wikipedia.org/wiki/Barsoom
Definitely way more fantasy than sci-fi, but they're enjoyable nonetheless.
For a more dramatic and dream-like take -- not "hard" sci-fi by any means -- read Bradbury's Martian Chronicles. I consider them to be masterpieces, though again, it's a softer, more mythological-like style.
Not much about the actual exploration of Mars, but a good imagining of the technology and politics needed to get there.