I mostly quilt straight line, not ness stitch in the ditch, b/c I am not very good at free motion. If you decide on straight line of any kind a walking foot will be your friend.
I only QAYG, I have been unable to wrestle a full size quilt under a dsm. There are many ways to QAYG, I have tried most of the ways I know of, and quilted quilts w/o sashing, w/ narrow plain sashing, w/ wide pieced sashing, on point, w/ fleece backing. I have combined different types of QAYG techniques in the same quilt. The only quilt I can think of that wouldn't work in a form of qayg is whole cloth.