What type of unit configuration is more stable for an investor in an apartment complex.

It will add to your costs and complexity of your business.

I want to know if any has experience offering law enforcement, govt employees, etc. a discount on rent, or perhaps having a program where you let them live rent free (assuming a larger complex of course).

@Carlos Leyva depends on what the majority of the other buildings/complexes are doing in your area.

I would be looking for Apartment Complexes. 

They're pretty available, can probably pick a blank up from a big apartment complex and customize to suit your needs. 

If I had the same "problem" I would put it all down on a multi-unit complex and work my way up to apartment complexes that could afford a Property Management Company.

Would anybody recommend a brokerage or realtor that know about which apartment complexes are for sale?

That is why you may have to do two closings and budget for both of them in an attempt to not let the seller that you are making a profit on what you are doing.In this economy Fix and Flip may be the best way to go including the borrowers that are willing to finance your repairs or rehab or to purchase multiple unit houses with a loan that the FHA will provide you with a low down payment but it is only made to an owner-occupant for regularly 12 months and you get to keep that same loan if you even when you choose to move away.Another thing to consider is to buy apartment complexes and take the advantage of positive clash flow and using a cap rate to increase your value on add-on properties and raising the rent. 

There are plenty who do things to help raise up their communities, and of course naturally when you get into apartment complexes large numbers come with the territory, but so does syndication which tends to water those numbers down again.