Here's how this layout would work going both directions (the center would be a pale background similar to the other backgrounds). There would be lots of partial seams if I use this layout.
Or I could stagger them in vertical columns, which still gives me diagonal movement but also creates some interesting shapes in the negative space. No partial seams here, just columns.
As long as I stay away from a plain boring straight setting, I think I'll like whatever I come up with. I'll figure it out when I get the blocks back from my friends and see how many I have/need and what size it comes out to. This will be a donation quilt and my plan is for it to be suitable for an older boy.