The Lake Superior one is pretty clear as there is only one road around it but Michigan routes are fraught with choices and unfamiliar territory. Advice as to direction around what to avoid near Chicago would be appreciated !
I did Lake Michigan on May 27 of this year (Memorial Day). I went through Chicago between 6:00-7:00 am, took I-294 around the city and didn't have any trouble. I did order an I-Pass (which is also used on the EZ-Pass system) and I didn't have to stop and pay any of the tolls around Chicago. It also helps that the tolls are less if you use and I-Pass than if you pay cash.
The route I used is below. The slowest portion was actually from Marquette MI to Marinette WI. The speed limit is 55, except for a short section north of Gladstone which is 65. From Marinette heading south the speed limits increase to 65 and 70. Speed limits on US2 from St. Ignace (Mackinac Bridge) to Gladstone are 65. M28 is also 65 from I75 to the Marquette area.
One note about Lake Superior. I did that one on July 13. The passed through Two Harbors MN heading south at around 4:00pm. The traffic was ridiculous since its a two lane road passing through the town and the tourists were out in force. Probably added at least 20-30 minutes to the ride.
One last thing (which you probably already know): when riding near the Great Lakes make sure you're ready for any weather conditions, especially sudden drops in temperature.