Indeed you’re right, one of the things about trying to do a moderately readable chunk a week is that there are inevitably topics left on the cutting room floor, or at least for future episodes. One of my favorite examples (because it’s so direct and clear) of what you’re talking about is this guy: http://www.rockslidephoto.com/leaf.php?id=2093&gallery=10

I would like to stress a point which is only hinted in the end where you discussed the sunflower photo:

Symmetry can be very harmonious with asymmetry. It actually enhances and amplifies the effect of the asymmetrical element in the photo. At the same time, asymmetry helps eliminate the boring static feeling in a totally symmetric composition, by adding a little movement that breaks it. So they complement each other.

All of the examples in this post (except maybe the first one) demonstrate it very strongly.
In the sand tufa photo, it is the little half-moon that breaks the symmetry (and amplifies it at the same time) and makes the photo what it is (Remove the little moon and the magic is gone IMO).
In the old marina photo, it is the asymmetric rock placement that complements the symmetry of the moon and the horizon. This photo wouldn’t work as effectively without either the rocks or the moon and horizon.
Finally, as you said, the diagonal stem complements the symmetric placement of the petals in the sunflower photo.

Keep up the good work 🙂

Noam