AZ and Hawaii experience ranges of [10-14 hours] and [11-13.5 hours] of daylight across the whole year, respectively. More southern latitudes can get away with not shifting their clocks because the daylight variance is much smaller. In AZ, sunrise varies from 5:15AM to 7:25AM. In Seattle, without DST, it would range from 4:11AM to 7:57AM. If we use "civil twilight" (bright enough for outdoor activities), Seattle would start experiencing daylight at 3:30AM in mid-summer.

Having 16 hours of sunlight in the summer means the sun is going to be up too early. Both 3:30 am and 4:30 am are way too early for the sun, but such is life. Either way, the sun is up well into the evening, so it's not as if much changed with an hour moved. Except the sleep disturbance; for some, it's no big deal; for others it takes weeks to recover.

Here is a reference point for Europeans: Seattle is at the same latitude as the southern border of Germany.

Where do most people in AZ live relative to their time zone? I wonder how apparent these issues are to people in DC; they're very apparent in places like Michigan, on the edge of their time zone; you drive for an hour outside of Chicago and it's weird how long the sun is suddenly up.

The state pretty much spans the width of mountain time. It's pretty large geographically, almost 350 miles across.