You could try playing around with different arrangements for your blocks. Are you committed to setting them on point? What about trying them out with a wide sashing between them?
I think that possibly the thing you are not liking is that the brown is high contrast, while the other fabrics are rather blended, so you end up focusing on the randomly placed chunks of brown. The fabrics are lovely, the idea of using large pieces is good, given the fabric line. You have all the elements there for a very pleasing quilt. Maybe just play around with the blocks some more to see if different arrangements make you happier.
RST