I did wavy lines on each side of each edge. The quilt has a slight water/Hawaiian feel to it, so the waves fit really well!
The only problem I had was with the back. It is a (very cute) plaid, but I didn't stretch it quite correctly on the frame and I think one edge will be a little distorted. So with this quilt I learned that it's really important to have enough extra to clamp on to, especially it there are straight lines on the back.