There's another new map of Mars out on the net, this one showing high-energy cosmic radiation exposure probabilities at the Martian surface.

Not surprisingly, the area with the lowest estimated rate of exposure is Hellas, and the highest rates are in the highlands of the Tharsis bulge (though, curiously, Olympus is relatively low-risk compared to the rest of the Tharsis volcanoes).

I guess I shouldn't be surprised that the most interesting places to visit on Mars are also the most "risky" by this evaluation. The question to ask here is, how does that risk compare to the increased cosmic radiation risk at high altitudes on Earth (say, in commercial airliners or even Denver)? A spectrum of "Moderate" risk to "High" risk doesn't really provide information that one can relate to.