I really dig this design... really looks fun and has the imagery i had in my head... it looks good. Is there a way to put the subscript in there? I guess it might look a bit crowded... or off balance with too many words.
oh, and as far as a the number of colors... less might be more. I do like #15 more than #16 with those hash marks like a plan view for a street... something in between the two as far as colors would be cool to see. Just for printing purposes
Could we try the grid a little darker? I really like the concept of it being both like a city and like farmland from above, but I want to make sure that it prints clearly in different scales.