That's totally a personal call. Some people would be OK trading a bedroom and bathroom to be able to walk home from the bar. Others wouldn't.

But the obvious criteria universally apply: commute time, square footage of the residence, crime rate in the area, quality of the local school district (YMMV), etc.

Most people when moving to a more expensive city compromise at least a little on all of those to keep rent manageable. So maybe a Bay Area resident spends three times as much on housing but they get half as much square footage and a much longer commute.

I agree that is the best way to think about it, but it means discussions about CoL differences are inherently subjective.

Perhaps, the least bad way to figure out what an equivalent salary in RDU and the Bay Area is to use revealed preferences and look at people that move between the two areas and what they are paid in either city.

I rented before, so I considered equivalent to be the same sqft (900f sqft), same quality neighborhood. I'm sure you could save some by getting a roommate or smaller living arrangements, but that wasn't what I wanted to compare.