Update: Areas in red show "rhotic" areas of rural England before 1950, iin answer to Sarang's excellent question.
"Of hand, of foot, of lip, of eye, of brow"
There is another metrical joke of a sort. That's like the stupid high school teacher's idea of what iambic pentameter is: five feet that are also five phrases. The infinitesimal minority of lines are really like that. ("Devouring time, blunt thou the lion's paw.." That's more typical.) The joke is on the Petrarchan "blason of sweet beauty's best..." The implication is that it is monotonous and predictable.
The other thing I've noticed recently is Thomas Hardy:
"But that I thus found lacking in your make
That high compassion that could overbear
Reluctance for pure loving kindness' sake"
That briefest, awkward and poignant pause before the word reluctance gets me every time. You have to stop one r sound and begin another.
Frost's "Silken Tent" describes a tent swaying in the wind, controlled by "countless silken ties of love and thought," but bound by no "single cord." There is tension and looseness, then, a swaying or swinging motion. The tent is the poem itself. This is a kind of higher onomatopoeia, where the prosody doesn't mimic sounds, but the structure of psychic events. Williams' cat climbing down into the empty flowerpot is another example. The cat is noiseless, but the poem moves with it. Campion's "Rose cheeked Laura" does it with sound, so there's that too.
None of this is news, but I have to keep reminding myself of the basic thing that makes poetry valuable to me, which is that it is an art form. Even the students who hate literature (they say) respond to things like this.