Even the hedge funds as far as I know were never really able to crack this code without a lot of work and boots on the ground so it will be interesting to see how they evolve.

Not broken but a preference item  code lock?

This new law is a perfect example, the government does not want these people on their rent rolls and therefor finds ways to force private landlords to take the risks.In my jurisdictions landlords, in order to protect themselves, are often forced to bend/break human rights codes in selecting applicants.   

Surprising since you are already a landlord that you do not know your state landlord tenant regulations.You need to look up your state landlord tenant codes regarding non renewal and evictions as well as contact the local welfare office to get the answers.

For the best value and slightly "young person" leaning, what zip codes should we be looking at (e.g., good mix of fun experience and cash flow)?

The community I grew up in had height limits on buildings at the city code level.3.

Heck, you'll be implementing CA codes and seismic loads. hehe

Read/study your state landlord tenant codes and determine how to remove tenants. 

For Memphis investors:  Which zip codes will you absolutely not consider?

I'd proceed with caution and spend some time learning the zoning code.