Cathe,
McTavishing can be done much larger to achieve the desired effect, look, & feel. You do not have to stitch it out small and dense. Lin posted some beautiful pictures of her version http://www.quiltingboard.com/posts/list/2463.page
You will see how she varied the sizes of her designs to add visual interest and different textures, which will also keep it from being stiff (if done on a larger scale) and give you the drape you are wanting to keep in your quilt.
As far as the loft, Pam is right in telling you to experiment with different battings until you find the one you prefer. You might like a wool batting as it will quilt nicely, pucker slightly, but still maintain a little loft, and no matter how much quilting you do, it will drape beautifully.