Amenities, stay fees, wow factor, location, and unit price are only part of the equation.

There are a lot of factors out there but savings is a lifestyle and some people are just incapable making sound financial decisions. 

Assuming that doesn't include any mortgage pay down, you need to factor in capital gains taxes. 

The ideal asset allocation for someone in your financial position depends on various factors, including your age, risk tolerance, retirement goals, and current lifestyle.

Closing costs, commissions, property taxes, utilities, interest, and many more costs are always a factor.

You didn't cause the problem which is a major factor in the premium impact.

Timely payments are one of the largest factors in a credit score and if he hasn't had late payments since then, his score would continuously improve.

The most major factor in most markets is affordability.

is there a particular formula that takes all manner of factors, (employment growth, corporation development news, barrier to entry, rental rates, wage growth, etc) into account and spits out an "invest in city X" answer?

This may not seem like a big deal, but it is something that you will need to nail down and factor into your analysis.