"An interesting analogy, but with a couple of holes. I dare say that if the Moon had been a bit larger, and had an oxygen atmosphere, plants, and water, that we would be trying one hell of a lot harder to get there than we are."
I think the Moon is pretty good. If I could choose, I think a smaller Moon might be better. A Moon the size of Mars (twice the gravity) and with some atmosphere & say 100 times the amount of water as the present Moon might be better than the Moon, though I think a moon 1/2 the present mass & with 10th the water, but concentrated enough to be minable would be better. But I'm not very picky, I think our Moon is good enough:).

"I also think that if the western half of the United States actually HAD been comprised of middle-Sahara type dune desert all the way to the Pacific, the "great American movement westward" would have been not so great."
The pacific coast would probably be part of Mexico & Canada, instead of USA- though it's hard to say- maybe it would become a independent state that maybe including Texas.

"Now, if the equivalent of California gold can be found on the Moon,* we might have something."

Of course this has already been *found*: water at lunar poles. During Apollo proram some people had suspected there was ice at the lunar poles- what if NASA actually had the "right stuff" and had explored the polar regions. Make good subject for a book, lots of possible outcomes and ramifications. But again, I'm not picky, and probably best if we go now, rather than having it happen way back then- NASA would have probably be about 100 times it's current size if they had found water on the Moon in the 60s & we could possibly be even further from CATS.