CHICAGO—As reported in GlobeSt.com yesterday, JLL's 2015 Digital Skyline report shows that the gap in rental rates between the top office properties in the US and everything else has widened to historic proportions. And although the premier spaces in many markets still have some room for even more rent growth, the tremendous expense has also helped push a growing segment of tenants away from trophy buildings in favor of non-core class A and class B buildings, inside and outside of traditional CBDs.

“In the past five years, we've seen increased growth from tech companies,” architects, advertising firms and many other companies involved in creative work, Julia Georgules, vice president, JLL Research, tells GlobeSt.com. “In general, they want architecturally-significant space,” and believe that a building's character can have an impact on company culture.

This desire leads the creative types to look for spaces on the peripheries of their downtowns, because the historic buildings with the proper character “are not right in the central business districts; they are in areas with a mix of property types.” She points to Chicago's Fulton St. Corridor and Manhattan's Midtown South as perfect examples.