I missed this thread before, but it's astonishing. I can't see all of the screenshots in the opening post, for some reason, but the bits I can see are absolutely amazing. I loved Sn00py's terrain but this looks to me to take it to another level. The sea alone is extraordinary (and I hate the continental shelf look, too).
I don't know why William is convinced that CivIII Plains are meant to represent wheat fields. If that were the case, they'd produce more food than Grasslands, not less. And you wouldn't find them all over the place before anyone's worked the land, either. They're meant to represent open land that is less well watered or fertile than Grasslands. Wheat fields would be represented by Irrigation, which is why there are some terrain packs that replace the Irrigation graphic with little fields (and which look splendid, I think).
[EDIT] Now that I can see the opening screenshots, for some reason, I see that Ares has included the "field" irrigation in this pack. Good work!