I am still following one CA ski town that I already own in, otherwise I am going to concentrate out of state going forward. 

I am hoping someone can either answer, or point me to resources so that I may educate myself on the geographical concentration of 2,3, and 4 unit multifamily properties.

There is another issue about doing refinancing and that is the concentration of loans to one customer.

In my opinion you are not concentrating on the appropriate financials. 

I am also investing out of state and mostly concentrating on A or B+ areas in TN, TX, OK, AR, AL.

Second, the housing authorities have a public policy interest (and pressure from the federal government) not to concentrate voucher holders in bad neighborhoods.  

Find a tenant segment with a high concentration of people who: pay all the rent on schedule; retain their jobs in turbulent economic times; stays for many years, and take good care of the property.

I had some clients close on a duplex there years ago and you’ll see some concentrations of small multifamily properties in that pocket. 

Concentrate on the 40 year plan not the 4 year one. 

If you are Looking for 15% passive cash on cash return you need to determine if this will come from rental income, flipping property or a combination of rental income and future profits.If your intention is to net 15% will that be from rental income alone and will you use leverage to get to that number.Once you decide on your objectives than it will become clear as to which market you should concentrate your efforts in.