Public transit can take you from the Loop to Aurora. I haven't tried taking this route yet, though. You can take the Burlington Northern Metra train from Union Station to the Aurora stop, then transfer to a bus or take a cab for a short ride to the outlet mall. Google Maps integrates with Chicago area transit (RTA) maps and schedules. You can Google Map the route from your hotel to the outlet, and select "by public transit". Specify what time you want to leave or what time you want to arrive, and Google will calculate a transit schedule for you. The outlet's address is 1650 Premium Outlets Boulevard, Aurora, IL. Once you have the route info you can also visit http://www.metrarail.com and http://www.pacebus.com for more details on your routes. The outlet mall's website is http://www.premiumoutlets.com/outlets/outlet.asp?id=63. Transit info is here: http://www.premiumoutlets.com/outlets/directions.asp?id=63
Depending on where you're staying, ask the concierge about shuttle buses to the Premium Outlet Mall in Aurora, or you can also call Guest Services (or whatever they call it) at the outlet.
It's easier to get to Aurora via public transit than to Pleasant Prairie, WI. I don't know of any transit routes to there. Since you're only here for a short visit, you're better off visiting Aurora since it's our Coach "flagship" outlet.
Good luck and enjoy your visit to Chicago and the outlets!