Maybe go for a primitive or embroidered style with crochet cotton, not too big a stitch (small fingers could get caught up). Fly stitch (turkey tracks) or feather stitch can look really good.
If not tying...would really firm french knots be ok? I am very keen on reading what others have to say. A baby quilt is in my not too distant future, so I am keen to learn more about "baby friendly" quilting tips.