> Phoenix is interesting but 1) very small and 2) in Phoenix, which will struggle with summer survivability by the time my kids are middle ages.

I'm generally in favor of long term planning but in this case isn't #2 kind of going overboard? Their middle ages are ~35 years in the future. A better childhood will probably be worth them having to move 30+ years later. Heck, there is already only about a 50% chance [1] that an adult is living in the area where they grew up and that's just due to the normal ebb and flow of the economy.

[1] the surveys on this vary a lot. 50% looked like a reasonable average of several that showed up when I Googled.