I think the question should really be "Coop for hot summer, cold winter areas", because if their housing can accommodate both most breeds will be totally fine.
I have English Orpington in Florida, LOL.
His coop is in deep shade under grandaddy oaks and is mostly open-air.
I wouldn't put him in the shed coop which has only adequate ventilation. Or the sunny open-air one.
The open-air shaded coop is actually cooler than anywhere else in the yard on those super hot days.
So, what does your yard offer in the way of shade and general topography?
3KillerBs has had some excellent ideas about working with microclimates.
I'm trying to remember what Twin Falls looks like, I know I flew in and out of there on training flights from Boise but I might be mixing it up with Pocatello. One of them is very desert like....
So, If I lived somewhere desert like (such as Arizona) with no natural shade, I think I'd dig down about 4-5 feet, put a short block wall around it to keep water out, then hardware cloth up to the ceiling all the way around. I'd make the roof waterproof and sturdy and put down top soil and sod, or a garden on it. Leaves reflect the sun really well.
Oooh, what if the roof could also be the run?
