I have used Minky (from JoAnn's) for 30"x40" approx quilt. I pinned the quilt top with ALOT of pins since Minky tends to shift. Once I had the Minky nice and tightly pinned, I did straight line sewing (in the ditch actuallly) and didn't have any issues.
Minky is hard to sew with, from what I have found, because of the shifting so much. Pinning every couple of inches while making sure it is tight has helped greatly.