I like the version with the sashing. I think it's more restful to the eyes, and with these colors -- that just makes sense to me. If it had been done in shades of red and gold (think autumn colors), then I can imagine it without the sashing and it would remind me of falling leaves.
I think it will be easier to quilt if you have the sashing too, because you can do something cute in the sashing areas that will tie it together with the outer border. Also, I think using the sashing makes your border fabric look intentional -- and not like an afterthought...