Depending on what kinds of deals you get you might be better off renting a cheap car for the trip. It's not like you're going to be able to walk out of your hotel and go to GG.
I can fly to match anothers arrival time, I have no prob chilling at O'hare waiting(there is a bar, right?!) for someone so we can split the cab or even better, call the BlueBMW Taxi Express! My Friday arrival options are: 8:29am, 10:50am, 12:41pm, 3:26pm, 5:16pm, 7:12pm, 9:24pm.
Public transport looks like 2 hour trek but you pass right by GG on the way to Red Roof. (I think out-of-towners should all stay in the same hotel so we can after party!)