I confess I had to look at a map of the larger Phoenix area to get a hang of this discussion. Glendale (and Surprise, what a lovely name! There's a story?), the Gila river itself, Phoenix, Scottsdale, the Salty river (of mostly Canadian tears?), Tempe. It's quite a wide area. Obviously it pales in comparison to the biggest* cities in Europe but it's quite big nevertheless!
I sort of get or can guess the pop density and the driving distance/ease arguments for and against. One thing I didn't get from the maps: where does the light rail run? (And is it like a "tram" as we call it or something bigger like trains proper?)
[*Apparently the city of Rovaniemi in northern Finland is officially the largest city in the European Union, with some 8,000 sq km within city limits before the 'burbs start. The 60k+ city folks are reportedly quite proud of this.]