I think a meandering or loose stipple would be a fun way do deal with the crazy blocks.
If I were doing it, I would use straight line quilting on the sashing -- probably 3 or 5 parallel lines in each sashing row, forming small squares in the intersections. It would make a nice contrast to the "free" and randomized blocks.
Another idea you could try, depending on your comfort level in free motion quilting, would be to hide a doodled shape in each block, probably in the larger, center block area. So it would give it a little bit of an "I-spy" flavor -- find the flower shape, the fish, the house, the car, etc.
RST