the quilt is lovely and I don't think you would hurt it with any pattern you choose... I think the spirals sound good, I think the stitch in the ditch sounds good but it would be so busy that I would probably modify it to be on 'certain chosen' lines, not necessarily the same ones in every square, something that wanders across the quilt here and there... just close enough to hold the batting in place... it is a busy pattern and i don't think i would put a ton of busy stitching on it, but either the spiral or 'limited stitch in the ditch' would be great... if you are putting borders on (i would, it will calm it a bit, letting the busy be busy and the plainer border be calm), there would be a place for a bit of curvy, smooth lines if you like... but i have done a lot of 'following the block design right off into the border' before... it works great, too.