Backyard Flooring Options for Triplex

[Michael Chow]

Hello,

I'm engaged in redoing the flooring in part of the backyard in a residential triplex. When I bought the property last year, there was an larger platform deck that was not property supported, was painted and rotten in many places so I tore it down and rebuilt a smaller 60 sq.ft. for the exclusive use of one of the tenants.  You can see in the picture (in the barren areas) where the old deck was.  

Additionally, the terrain is a bit uneven and I think re-grading will need to be addressed as part of the work as the land, beginning at the rearmost lot line and moving towards the house to roughly where the grass starts, seems to be sloping towards house (see pictures).

One other tenant has a walkout balcony in the front where he has a BBQ set up so he only uses the rear yard to let his dog run around and "use the washroom".  The basement tenant has a dog too but no deck/walkout area so I can see him possibly wanting to set up a BBQ in the new back yard.  

I'm looking for opinions on cost-effective options to address 1) the grading and 2) re-flooring the barren areas given that the backyard (not including the small deck) is to be shared by all tenants.

Should I just regrade and re-sod the sloping section and then re-sod the barren section?Would it make sense to spend a bit more to put in large patio stones in the barren section?