You sound like a fairly conservative pilot so I suggest that you not fly over Lake Michigan on you way to Grand Rapids. The consequences of an engine failure over an 80 mile wide lake are not pretty. I suggest filing to the Peotone VOR (EON), MAPPS intersection which keeps you away from ORD's airspace, then South Bend, then Grand Rapids. If you do fly over the lake, take water survival gear, life vests, life raft and EPIRB. I fly in this area a lot (based in Toledo, OH) and the bottom of Lake Michigan is littered with aircraft. Just last week, they pulled a WWII trainer from the bottom of the lake to restore it. In the summer months, there is a Coast Guard helicopter stationed at Muskegon, Michigan to fetch boaters and flyers out of the lake. If you decide to cross the lake, use the Lake Reporting Flight Plan. This is a separate flight plan for VFR use only, that you file with Flight Service. You contact FSS every ten minutes while over the lake. If you do not respond in five minutes after your ten minute reporting time, they launch search and rescue. Contact FSS and they'll tell you all about it. Have fun!