This is very good thread Scott. Even so good that I'm not sure I can add any intelligent questions or comments here
But answer to your question about which elements outside of the scroll have their rhyme. I see two things actually - all those little 'things' (floral vocabulary lacking here) pointing outward, and inward too, are equally spaced. Some of them with grapes. Second thing, If I use my imagination, then I could form a rectangle of outer elements - 2 grape bunches on the left and 2 leaves on the right. Sort of rhyme, right?
It's little bit off topic, but I have to ask. When you start a design, do you really think about all these things you've talked about here? It seems like million things to keep in head at the same. Distance here, rhyme there, leaf here and there, not there etc. I think and hope that it comes naturally after a time. I draw a backbone, it looks little off here, correct it. Draw a bunch of leaves and correct them until it's pleasing to the eye. But of course I must know why it looks bad and know how to correct it.