Raggedy's most recent photo thread has actually given me a new appreciation of the viaducts:
http://forum.skyscraperpage.com/showthread.php?t=174493
They really aren't that bad and it would not take all that much to further integrate them into the urban fabric. With dynamic lighting, painted murals and extensive landscaping, the city could turn the area underneath the viaducts into a vibrant mutipurpose park for a relatively low cost. I'd even be in favor of a 'viaduct park' replacing the proposed park in NEFC.