I would keep it simple, so it will stay soft. I have overquilted quilts which makes then too stiff. Just stitch in the ditch with a single cable/rope down the white spaces.

I don't know but it's so pretty!!! :)

Thank you all for your great ideas. I am in the middle of quilting as we speak - but ran out of bobbin thread so need to make a run into town! I used someone's suggestion and am stippling all over with a verigated thread. Will post a picture when finished. You all are such an encouraging and inspiring group of people!