Things to note:

Just be safe if you go to the downtown area, watch out for people coming up to you trying to sell stuff, its not Jordan..be firm and say no, no eye contact move fast. Homeless there are mostly drug addicts and alcholics, hustlers and thieves.

Chicago has a big problem with gang violence, so make sure you aren't in the ghettos i.e englewood, south side, riverdale etc..your friend should know (or go during the day, again, move fast serious and focused, stay alert).

Stay high end Chicago, it's pricey, but fun, i.e Lincoln Park, Norwood, Edison Park, visit uptown chitown for the clubs, cool venues.

Best of luck!

Source: All my life in 'Murica, born and raised.