I agree that there are many ways to quilt a Bargello. I stitch in the ditch, mainly because that is my preferred way of quilting. I just like my piecing to be the focus and not the quilting....just me, I am weird that way. I don't stitch in every ditch, because there are too many in a Bargello, and I use Warm and Natural, so I don't need to stitch too close together. So I usually end up stitching every five or six inches.
My quilting really doesn't show, but I will attach a picture so you can see it doesn't show.
Dina