They need to be the kind of product that you believe is desirable to your customer base.

This city is desirable, I buy in good neighborhoods, etc.

I am not aware of any efficient way to filter through properties other than looking at all of the properties in your desired location, and checking to see if it has a basement apartment.

I want to store my money in desirable hard assets.

The secret of getting ahead, is getting started.It is vital you connect with a realtor anywhere in the United States, who will take the time to understand your desired type of property and areas of the market you have been looking in.Learn about the good, bad, and ugly regarding distressed properties, whether due to  property condition or the chain of title.

.- 2-4br single family homes are super desirable among voucher holders. 

I am new to real estate investing and I have do have a deep desire to make it work.

If you really mean that all 4 of you are on title and mortgages for both properties, then you may want to look into methods to clean up title, if you desire to separate from each other. 

Typically, the higher pricepoint/most desirable househack markets will take the longest to cashflow.

Estimated home price based on comps is $250-260k and rentals go for $1,700-1,800.We both believe that small multifamily properties are the smartest way to start given our ages and desire to probably retire by the time I hit 70 - 10 years from now (if we want to).