I travel to Chicago frequently and entertain there alot, so if you could give a few more details, we hounds could be more helpful: E.g. how many? budget or expense acct? general age group? do they have to catch the train after dinner? etc. For example, I would guess that "hip" would immediately rule out most of the beef barns (S+W, Morton's, Capital Grille, Keefer's etc.). How 'bout MK, NoMi, Spiaggia, or Topolombampo, just to name 4 different cuisines and atmosphere? Give us some help.
980 North Michigan Ave, Chicago, IL 60611
5340 N River Rd, Rosemont, IL 60018
A few other details will be helpful as well. What about attire and cost? Some groups might enjoy dressy, expensive restaurants like NoMI and Spiaggia (e.g. where jackets are appropriate for gentlemen and dinner might run $150-250 per person inclusive), while other groups might rule out such places. Also please mention where people are coming from; if visitors from out of town are involved and are staying in a particular hotel, a location convenient to the hotel would be a plus.