Best floor plan for new 5-plex rental

[Dave Janis]

I'm building a new set of row houses to be used as rental units.  The units will be 20 wide by 30 deep with no garages (600 sq ft a floor).  Here are the questions I have on layout:

1)  I can go two stories tall with a full basement - or - three stories on a slab - or - 2 stories on slab

2)  What is ideal mix?  2 bed 3 bath, 3 bed 2 bath

3)  It is in blue collar area walk to light rail and being gentrified.  If neighborhood was better I would build to sell townhomes.