The granite is a nice material but like everything modern in this dreary city, it's grey and barely stands out from the surrounding concrete. It's probably a big waste to trash all that stone but using a warmer colour would be an instant improvement; add some seating and you're getting close.
Pioneer Courthouse Square in Portland and Fed Square in Melbourne come to mind as a couple of ideas to emulate. Warm, red tones used for the paving materials and the use of elevation creating an amphitheatre effect, as well as large stairs that serve as seating.
From there I'd ring the square with hardy, fast growing trees and look at creating a more intentional, grander water feature that really impresses. The Crown Fountain in Chicago comes to mind, although probably a bit too large/ambitious for this location. Surely we can find some middle ground though.