We've traveled I-80 skirting Chicago several times heading both east and west.  Timing is EVERYTHING when running through there.  I'd try and time it so you're running by Gary around lunch time maybe a little later.  It can be "fast-paced" going through there but if you roll with the flow you'll be just fine.  Keep in mind if there's an accident on 80 -94 all bets are off.  One thing I like to do is tune in WBBM 780 (AM) when getting close to the area, they have traffic on the eights and most of the time the info is pretty good.
Watch your timing and you'll do great. Once you get past the I-80, I-294 interchange it's pretty much smooth sailing westbound.
Dan