Sharon B was right in us this is an easy stitch and an attractive border as is. However, I couldn't think of much else to do with it other than vary the stitch horizontally or vertically. Here's what I did left to right:
The right branch experiments with horizontal variations. I might have avoided the "nubs" if I had made the changes more gradual and by paying closer attention to the tension.
3. Exactly like #1
4. Upper portion of this column is worked evenly but more open. Below I worked two side by side rows.
5. Didn't want you to think the squiggles in Column 2 were mistakes. Here's an entire column done zigzag style with random stitch length variation.
6. The final column show a gradation in stitch length.
I don't particularly care for this stitch on its side, but I think vertically it doesn't make much difference upside down.