[Jibba]

I'm actually enjoying the rhythm of the setbacks on these. The visual trajectory of them nicely decelerates as the tower climbs skyward, and they don't come to a screeching halt at the top. I usually prefer the inverse setback pattern, where they decrease in frequency as the tower reaches skyward and with increasing distance between them (this trajectory is continued virtually in the mind even after the physical tower stops, giving it a dynamic of infinite upward movement). With this proposal, it's a terminal procession of energy but a complete one, and then the eye is drawn back to the bottom to cycle through it again. (The Jin Mao is an example of a tower that to me doesn't succeed with this scheme; it feels like the energy is stunted, and by the time you reach the pinnacle, it feels like the tower is decaying into itself.)

Though, I still prefer the effect created with the Tribune proposal's incomplete arch--the tension you feel as the arch at the top strains to climb and complete itself. It gives it an enduring energy of ambition and reach that results in a different kind of dynamism, like there's a string running through it from the ground up, pulling it skyward.