Hmm, interesting that Spudis is so confident and expects more than 10 billion metric tonnes of water at poles.
I believe the best place to go is lunar poles. If we decide to go there, I believe we will find some pretty interesting things.
I don't think Zubrin gets it [or more likely, he is deliberately ignoring the obvious], quantity isn't really that important. If you could easily harvest say a few thousand tons of water this would be very significant (10 million lb at say $5000 per lb represent of value of 50 billion dollars). What's important [economically] is how accessible these water depost are. In other words if we knew the location of a small pond of ice at a lunar pole and it was in a "good location" for lunar operations, that would probably be enough.
With a couple of tons of water (plus the energy to split it) it gets a crew off the Moon. If you can have a supply of rocket fuel at the the Moon then you don't need to drag your return fuel all the way from the bottom of Earth's gravity well (you have more than doubled your payload for any mission requiring a return leg). With a thousand or so tons "you can look" at exporting it to a lunar orbit [this then allows even less payload mass in order to get to the Moon (or Mars)]. With million tons it makes exporting to Earth orbit a possiblity- though other sources such as from NEOs may at this point be more profitable.

Suppose Earth had two moons- one like the Moon and the other one the size of one of Mars' moons- say it was in one of the Earth/Moon L points. [IMO] Economically we wouldn't be as interested in the Moon as in the smaller moon- because it would be cheaper to get the smaller Moon. The smaller Moon would also have more value in terms of human colonization- because they would provide resources needed at lowest price. The value of this moon [least in the beginning] would be simply that it provided a platform- for space stations or communication satellites or whatever. In this reality you wouldn't have ISS in LEO- the small moon would be the obvious destination.
What water ice at the Lunar pole does at least in the beginning is merely lower the cost of doing anything on the Moon and this leads to lower the cost of doing anything in space.