In zoning districts where no more than three unrelated persons may occupy a dwelling unit (as specified in subsection 175-56 General Dimensional Standards), there shall be no more than three unrelated occupants in total for the single-family dwelling and the accessory dwelling unit combined or for the single-family dwelling and the accessory apartment combined."

We did a very nice total remodel and it is stocked very well- i.e more than 4 forks etc and tenants really appreciate it... coffee maker, spices, quality cookware, bikes, beach accessories.

Even allowing increased density within existing structures or modest infill development (accessory dwelling units or "granny flats" in backyards). 

I also just recently purchased my 2nd investment property in September 2015: a 3-bedroom student rental house with a 2-bedroom accessory apartment.  

@Kenneth Olsen There's a ton of HouseHackers here in WA - a combination of high-cost real estate and many cities (like Kirkland, Seattle, Tacoma, etc) having favorable accessory dwelling unit / backyard cottage laws makes this a great state for the strategy. 

I'd probably look for an area that allows for accessory apartments or try to do some kind of duplex.

I'm 39 and live in Yorktown Heights, NY where I own a house with an accessory cottage which I rent out.

It could be a good accessory apartment if there was access from the back

Most zoning laws in most cities do not allow accessory dwelling units, (ADUs) in neighborhoods with single family zoning.  

@Russell Brazil what about creating an ADU (accessory dwelling unit) indirectly converting a single unit to a 2 unit.