There is no guarantee you will see the Northern Lights, even if you are in the best areas. However, a bit of planning will increase your chances. Since darkness is required for the best viewing, the rural areas along the Lake Michigan shoreline are ideal for viewing.
According to Wikipedia, the time between 6pm and 4am is the most intense period of the day. The highest probability within this time span is between 10 and 11pm. However, this is only a guideline. In periods of strong activity, one can expect several flares starting at around 6pm, peaking around 10pm, and going on until 1am.
In the longer term, auroral displays are correlated with an 11-year cycle in sunspot activity; the more restless the sun, the more aurorae.