Um I've got a suspicion that the average "Liberal" Space enthusiast is too ignorant or too stupid to realise that the average distance from Mars to an asteroid in the main asteroid belt is much greater than the average distance from Earth to the same asteroid. I'm not saying that average distance is a key determining factor for intermediate bases, just that I've got a suspicion that the average Liberal Space / "Science" lover just imagines that Mars is analogous to the colonisation of the Canaries, say in the discovery and colonisation of the Americas by the Spanish (And their agents).
The Moon is plausibly useful, its only a very modest gravity well, but its got enough gravity to usefully hold things down. I'm not sure for example how the surface gravity of Phobos compares and the Moon has no atmosphere. Mars on the other hand looks to me like it has the ability to make Roanoke Colony look like a great success story of venture capitalism.
I'm the average Space enthusiast here, and what I say is that it will be centuries before we are ready to do a colony on Mars. It may never happen, because even after we get the cost of Space travel low, it would be the most expensive thing humanity has done by one or two orders of magnitude. It comes down to being able to develop a few technologies that could facilitate terraforming.
The mining thing is a simple progression. The Moon will be the beginning, but everything after that will require a multinational effort. That would happen because certain things, like rare earth metals, are important, and in limited supply. But, again, I expect mining the Belt to happen in the next century, not this one.
One minor point, the Belt is not friendly to living beings. Mining will prob be done by automated machinery, with remote control filling any gaps. There may eventually be repair crews, but I wouldn't expect anything like that for 200 or 300 years.
What I would like to see is long term projects that do things like investigate the ocean at Europa. NASA has done a ton of great scientific work, but if we were smart, we'd double their funding to do more.