Thanks for all the great suggestions so far. I guess I should have been clear - I quilt on a longarm, so walking foot designs turn into ruler work for me. I can do it, was just hoping to come up with something a bit easier/faster for this quilt. I want to submit it to a show, and the deadline is next Sunday.
I'm thinking about freehanding clamshells in the background, concentric diamonds inside the light grey star points to echo those points inwards, and in-the-ditch in the other points, with maybe some highlight in the teal diamonds. That's kind of my go-to default though, so something different would be great.