eventually I half-stumbled on the fact that the 24 column / 960 grid can be divided almost perfectly into a true golden ratio of 1:1.618. The larger space is 580px and the smaller 360px, becoming 340 with a 20px gutter between the two. This makes the ratio 1:1.611.
With these base sizes, I began experimenting with dividing further with the golden ratio, and also just simply dividing the larger space into two, leaving me with three uneven columns of 280, 280 and 340. What I enjoyed most about all this was breaking away from the same old and really trying something new.