Well,i would prefer it to stay in "Japan",or a land which doesn't exist at all. A custom one. Why? The regions had many aspects based on the islands but they're almost whole new world, the only REALLY Japanese things i remembered were Kimono girls. It was all mixed up,like a custom land.
I feel Isshu is based on NY a bit parodially. Soccer players were awkward,like all those businessmen etc. I think they really want us to believe we're in a bit parodied US. No idea why,but i don't think that's right...
There were actually lots of 'really Japanese' things in Johto. Because the place its based off is stereotypical of olden day Japan. The rest of the place is pretty well developed. Isshu isn't exactly a country western.