Not sure about the free motion designs. I think a straight line pattern done with a walking foot might look good on a southwest style quilt top. These websites have some ideas if you decide to try a straight line pattern:
https://venividivicky.org/2014/08/25/straight-line-quilting-patterns/
http://www.aqsblog.com/25-nine-patch-quilting-designs[SUB][SUP]