Your quilt is awesome and has great graphic impact. Because of this, I really think straight line quilting will work well with it.
If you are not comfortable with FMQ and you want to enter it in the fair then you should stick with what you are comfortable with and good at. The pieced design is very strong so I think it would be fine to do simple walking foot quilting. Google images of walking foot quilting. One great one I saw was a spiral radiating from the center using the width of the foot to space the lines apart. I think that would look fabulous with the graphic impact of the piecing on this.
Here are some links to help you with inspiration
http://quilts.dexear.com/machine-qui...-walking-foot/
https://www.google.com/search?q=walk...ih=907#imgrc=_
https://www.google.com/search?q=walk...lting+patterns
Use a very fine thread (invisifil, microquilter or maybe bottom line) so the quilting sinks down into the fabric and all you notice is the texture left behind.