If you want some simple ideas:
Put a simple cross hatch which you can do with a walking foot and light marking on the outer border, I would do a curved cross hatch in the triangles and the inner squares about 1" apart depending on the size of the quilt, and a SID in the blocks being sure they are close enough together other wise would repeat the cross hatch in them as well. For the curved, make a nice gradual line on the blocks and then just move down and mark again so you are sure to get it the same size. If they are smaller than 12" blocks, like 6", adjust to 1/2" apart. Does that help?
If you are set on FM and no lines, then feathers is the answer to me as well. There is always line dancing but you would still need to fill in the large blocks, then i would do a little Pam Clark design. Is this what you are looking for? what is the size?