If you're looking for just State Patrol coverage from Chicago to Madison, you'll just basically need two main frequencies.
The Waukesha Post covers from just west of Milwaukee all the way down to the WI/Illinois border and DeForest Post covers from just west of Milwaukee all the way to Madison. That basically covers the southern part of the state.
Waukesha Post - 154.665 (103.5) covers Kenosha, Milwaukee, Ozaukee, Racine, Walworth, Washington and Waukesha counties
DeForest Post 154.680 (136.5) covers Columbia, Dane, Dodge,Grant, Green, Iowa, Jefferson, Lafayette and Rock counties.
151.460 (146.2) is called Statewide and once in a while you'll hear it used also.