I like Bozeman as Zephram Chocoran’s home base because there’s a good chance that Montana might have been spared a direct nuclear strike. Same logic applies to why San Francisco looks so futuristic: it for sure got flattened entirely by a nuke, so they would have had to build it back up from nothing afterwards. I’m guessing the Golden Gate was still partly standing and they rebuilt it for the same reason we keep other historical buildings/monuments around.

No idea if any of that is canon, but if we aren’t overthinking Star Trek then why are we doing any of this?