Vernor Vinge has said that he drew inspiration for the planet of the Tines from a visit to Norway, and Amy Thomson told me recently that she traveled to Mongolia to get a feel for the planet where her recently-finished novel is set. If the otherworldly photographs George Steinmetz recently took in Bolivia are any indication, this cold, arid, beautiful country could easily inspire a novel about life on a terraformed Mars. Here, in the massive salt flats of Uyuni, you can see the pale piles of mineral that miners have chipped from the ground with pickaxes. A very thin layer of water over the salt creates a reflective surface. More uncanny images below.
Here you can see cacti dotting the edges of the salt flats. If you were going to try to introduce plants to Mars gradually, a succulent like cactus would be a good bet. Of course, that assumes that you've already introduced sufficient nitrogen to the environment, or have bioengineered cacti that could thrive in the Martian atmosphere — and in temperatures much colder than anything in Bolvia.
These are the mud pots of Sol de Mañana, which release steam and sulfur as well as hot mud. The strange blue cast to the mud comes from the scalding water reflecting the sky at dawn. This might be from the surface of ultra-volcanic moon Io, rather than anywhere on Mars.
If you want to see many more of the amazing photographs Steinmetz took, check out the National Geographic gallery. Thanks, Marilyn Terrell!