Braids work nicely. French braids look harder than Prairie braids, but are actually easier.
Columns of French braid look pretty spiffy but are not too difficult. I have attached 3 patterns that look good but are not hugely difficult. I did a demo of the waves quilt at one of my guild's overnight retreats. Everyone c ame out with a great quilt, with no 2 looking like the others. People played with all sorts of variants on block placement.