Holly,

The city and suburbs of Chicago are huge, thus it is usually best to split your time between downtown, and the suburbs.  Popular and safe areas include the Magnificent Mile (which is rather expensive), Schaumburg, Oak Brook, Naperville/Warrenville.  Try to avoid O'Hare, Elgin, Elk Grove Village as the quality of accommodations are less than desirable, and often draw the attention of LE.