Prism99

In my experience, softness of the finished quilt depends largely on (1) batting used, (2) type of thread used, and (3) density of quilting, in that order.

Warm and Natural batting has a stiff drape that softens up somewhat with multiple washings. If you want the quilt to be soft to begin with, I recommend trying Hobbs 80/20 or Hobbs PolyDown. These two battings also provide more relief to the quilting lines (compared to Warm and Natural, which yields a flatter finish on the quilting).

I have quilted very closely using Glide thread, which is a trilobal polyester, and the quilt remained soft. Close quilting with cotton thread in top and bobbin (King Tut) resulted in a stiffer quilt.

If you do the same amount of quilting (3-4") using one of the Hobbs battings and Glide thread, I'm sure you would find the result considerably softer. I really like the PolyDown for softness, but find that it is a little harder for me to quilt as its loft is "springier" than the 80/20.

One advantage of PolyDown, which is a polyester batting, is that the quilts dry faster than a cotton batting. They are also lighter in weight. This makes PolyDown a great choice for children's quilts (and also for large bed quilts when you don't want a lot of weight and don't want to wait 3 days for the quilt to dry completely after washing).

Edit: A lot of the show-winning competition quilts that are densely quilted are quilted with 100wt silk thread (which is very fine). I have no idea how stiff or soft those finished quilts are, but I do know that the same amount of quilting with King Tut would result in a lot of stiffness.