It's worth bearing in mind that space provides great height, stability, clarity, lack of weather, lack of atmosphere, infinite lines of sight, microgravity etc etc. These resources have used for decades -via robots. Planetary Resources Inc plan to try and get a more material kind of resource, also, if I understand things aright, using mainly robots.
The message my reading gives me is that space resources, tangiableor not, are better 'mined' by machines, with human oversight from a distance.
The only pull factors I can think of for manned flight are tourism, entertainment (I'm thinking of novel zero-g sports) and PR. But those things could work, if the prices come down enough eventually.
RE Antartica: I have heard that there are considerable mineral resources there, and that it would be profitable, albeit barely, to mine them, although it would make more sense to mine out easier to get at locations first. I'll try to locate reference.
In space PR and Politics are as important as engineering and science. And no-one can hear you screaming about it.
"There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy."
Exploring other worlds with people is a great idea, but look at what has happened since the end of Apollo: How much could unmanned exploration (and astronomy) have discovered with all that money blown on paper rockets?