I have a friend who makes 3 or 4 string quilts every year- she brings them to me & I quilt something swirly all over it generally- sometimes it has a definite pattern or color theme & we choose something special- but mostly something 'curvy' . she generally uses a warm & natural batting & a plain backing so I quilt it to look nice on the back- since the quilting mostly disappears on the top- but you can see the swirls. we usually choose a medium gray thread (or something that works with the backing-since there are so many colors on the top.