A couple things could be happening. If your quilt is heavily pieced, there are lots of seams which could contribute to a bit of stiffness. You also mention hi & lo loft batting. Are you using polyester or a natural fiber such as cotton, wool, bamboo or silk? I've only tried poly on a couple of quilts and thought that they were much stiffer than the natural fibers, but it may have been the brand I used. And finally, regarding the distance left unquilted. This is totally dependent on the batting you use. Read the label. Some batts require quilting closer together, like 3 or 4 inches, some batts you can quilt as far as 10" apart.