While it hardly ruined my vacation in Chicago (a great city by the way), I was greatly relieved to see that the crowd visiting the Art Institute had all Made an Effort.
This is not to say there was a fashion parade going on. It wasn't the Met Ball, nor should it have been. People were dressed appropriately (and comfortably) for enjoying the art and being in that great space.
I even saw a young woman evoking Audrey Hepburn and looking as lovely as the art herself.