Caves, caves, caves! Why are we not looking at Martian caves? Should people do it, or just robots?
I like the human exploration of caves on Mars thought, but then again we run into the cost issue. I guess if we're going to send people to Mars, that should be their mission mandate? I would think that it would be a serious option. Either that, or landing them close to Cydonia just to really see what the hell is down there. :)
About the caves though, I bet the risk of spelunking on Mars is better suited for rovers. Now, the people on Mars can drive the rover in real time, doing better research by bringing samples out to them and not having to deal with time delays, but actually going into an unknown area with a clunker of a space suit...hell, regular cave exploration on Earth is risky enough without that extra baggage.