Sure, so minimal commute times and affordability of family homes in areas with good schools should be very appealing to many of the specialized senior engineers.
Moving the family is a pain, sure, but that just means the pitch needs to include why it's worth it for the family. And it means that senior engineers move cities less often. It doesn't mean they move less altogether.
Idle thought: this kind of risk (moving around too much) could be mitigated a bit by some sort of contractually guaranteed employment. A move to Princeton from SF would sound better if a four-year employment guarantee or a comparable cash buy-out was part of the employment agreement.
Personally, I hate living in the tech hubs, I'd love to be able to move back to my hometown, it was a great place to raise kids, didn't have the same crushing traffic / monoculture and it was close to my family. I'm where I'm at due to the jobs, nothing else.
The job-is-terrible concerns can be addressed other ways. Like putting the candidate up in temporary digs for a month or three while they decide on a longer-term deal. A reverse contract-to-hire, if you will. That sounds complicated, but it's not more complicated than a normal contract-to-hire.