can you post a pic? I did a Bertie quilt for a customer and just used continous curves (you can even do those with a walking foot on a domestic) on the border squares and basically just outlined the applique, with some detail like you've suggested on the larger applique pieces. Or if you need more in the background of the applique (or embroidery), outline it first then just do squiggely lines in a thread color that is a "no-show"--it will add texture and keep it all together.