I am doing this post more as an experiment to see if I understand how the posting works than anything else!! I tried a couple of different techniques for finishing the scalloped edge. You can check them out on my blog: One Stitch At A Time. I think I got it figured out (the postings and the scallops) 
vpll1912project
Sewing the 1912 La Mode
I liked your three samples. I did a very thin bias binding and am not happy either. The piping is nice and lays so well. I wonder how it was done back then around those points?
I agree with sewweezee – I like the piping on the edge best. You could even use flat folded in half bias like piping – sandwiched in the seam instead of turned over the edge.
(Your post here with links is great – thanks for categorizing it too!)
Sewweezee – I didn’t look into the historical accuracy of the piping. It seems to me that they must have used piping as a decorative effect quite far back. I am not sure that it would have been applied the way I applied it.
With the cording in there I could tell if I was too close or too far away from that edge.
Brooke – I actually thought about doing exactly what you suggest but I was afraid I would end up with irregular widths of bias edge because I like to do things fast