The piping idea is a great one. As far as borders are concerned, looking at how it's presente here against the black background, I personally would put a thin back border around it first, followed by the piping and finished with the original fabric. I think the black border would (my favorite suggestion it seems) frame the piece. Putting just the piping followed by the original fabric would cause all your hard work to be lost...at least that's that I think.
Whatever you chose to do will be what you like the best, and after all....it is your quilt and made the way YOU wanted to make it! :thumbup: