Right side of the upper chunk:
Just a simple crown or architectural element at the top - with some subtle lighting ( NOT Vegas Style) - would go a very long ways in helping this design culminate or come to some visual conclusion.
Maybe a series of horizontal or vertical louvers or slats...like what Portman had at the top of his residential tower going up down the street.
It's a real shame we can't just apply the 30story Trammell Crow tower design to the 61 story tower - then we'd be in business!