I don't know what areas are technically possible either, but i'm partial to the International Gateway area myself. Something similar to this-
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From my admittedly very rough calculations, I measured this mockup to be approximately the same size as the show building for Disneyland Paris' version of It's a Small World. I'm not sure if this would fit properly here, but it's just a basic idea.
I'm already partial to Paris' version of IASW in general and would like to see it used as a template if it were to be built in this area (the facade from the original World's Fair version would work better nearer Future World though). The Paris interior has a mixture of similar scenes but also some unique ones. It also feels like the space is better filled out, seeming to do a better job at disguising the ceiling in some scenes as well. The loading area is also outdoors like at Disneyland, but covered for weather reasons. It's an elegant canopy adorned with antique looking trim lighting (much like many of the classical early 1900s buildings seen in Disney parks, including the World Showcase pavilions). The facade is similar to DL, but more colorful and (IMHO and no offense to the also lovely Disneyland original) much more elegant and beautiful.