I do not see why we should rush for human settlement. There are too many other things we can should solve about planet exploration, and worrying about where and how humans will eat and sleep on another planet should be the last thing we should worry about.
What we need is a 1000 more Curiosity probes and rovers - one more advanced then the next. To the point where the last few bots are basically humanoids that can basically live, explore, experiment, build, repair, etc, etc and be controlled by humans on earth. To the point where we have build a safe settlement for human occupation and we have repeated proven trips back and forth.
I think taking virtual exploration, advanced robotics, etc to the next level, will offer a lot more (and be safer, cheaper) than a narrow and single minded goal of human settlement only