How should I be thinking about the risk of air travel (re: Coronavirus)?

I don't know how much this one helps, but it's not on your list:

Take advantage of that vent above your head.

"Set your ventilation at low or medium," he says. "Then position it so you can draw an imaginary line of current right in front of your head. I put my hands on my lap so I can feel the current — so I know it's properly positioned."

Then if something infectious is floating in your personal space, he says, that air from the vent will create enough current to knock it away.

– Pathogens On A Plane: How To Stay Healthy In Flight

My understanding is that the air filters for the cabin air are very good.

Still both a mask, possibly eye protection and protective clothing and gloves will make the risk approach 0. I would also suggest staying away from food and drinks on the flight, 3 hours is not too long a time.

Since you probably will not be directly interacting with many people on the plane, your risks in flight are probably lower than going to the local grocer or drug store.

For a possible data point, I want to say I saw a picture of some of the evacuees and not all we're wearing masks. Given that I don't think everyone one of them tested positive I suspect the risk is limited to who is sitting next to you (window seat might minimize that) and the crew.

All of this is speculative, other than the flight air filters (high confidence that is correct).

I suspect you won't be able to estimate with small enough error bars to know whether the marginal increase in risk of infection by one plane ride is more or less than the reduction in risk by the more comfortable and (presumably) less metropolitan place in Arizona. My intuition is that if you compare it to any major coastal city, you're better off in AZ, even considering travel risk. Even more so if this is a change from urban to low-density suburban living and you do actually semi-quarantine (only go out rarely, and only at times of low crowds).

IMO, the main problem with flying is the airports, which have a high density of people who've recently been at a large variety of places. If you can arrange to fly to and from regional airports without international flights, that's probably a plus.

All that said, I still rate the overall risk for healthy young to middle-aged US urbanites to be fairly low. I recommend most of your optimization to be on the comfort and short-term-panic-survivability side of things, more than the minimization of exposure to the virus. For that criterion, AZ seems like a clear win for you.

With so many unknowns about covid, and how it's transmitted, or how long it remains active on surfaces, it sounds dicey. With a finite number of planes and the high number of travellers arriving @ places with the virus, you have to wonder if there are any planes left that aren't potential transmission transit tubes. So many places in those closed environments for covid to hide. I'm guessing the ability fully sterilize a jetliner has to be nearly impossible.