I always said that I feel like there's a great transition of style as you move across downtown...Spring and Bowie take several design cues from each other, as does 360 from Monarch..and will play off of Seaholm. Continuing, I believe Fifth+West will feed into GreenWater 1, Colorado's blue with Frost and the Austonian, Marriott's brown bounces off both One and 100 Congress, Four Seasons' pastels to the Rainey buildings and so-on. I think it's becoming, intentionally or not, a fantastically coordinated and harmonious skyline.
Also, speaking of Frost as iconic, I've always felt that Frost was like the Chrysler Building of Austin. It may eventually be overshadowed by other taller or more prominent towers, but its status as an icon of the city is and will always be uncontested.