Agree with Jan & Katier ... feathers or baptist fan are both good choices.
Generally speaking when I'm faced with a quilt that is all angles I like to soften it with curved quilting, and when faced with a quilt with all curves ... I like to throw in angles. Mixed quilts can be either ... or mixed
Another option is to quilt a whole design into the quilt ... for example a butterfly that covers most of the quilt and a filler around the butterfly to cover to the edges. Because the design moves across all of your light and dark areas, and log cabins are typically rather busy, you probably won't even see the design from the front. But from the back you have a whole cloth quilt.