If you are going to do sashing, go with the black. Sets the blocks up very nice. I normally am one for sashing on scrappy type of blocks, but the layout without the sashing really appeals to me. No matter what you choose, there needs to be a small inner boarder to kind of stop the busyness before she adds the final boarder. I would use black for this. Can not wait to see the finished quilt. It is going to be wonderful!!