I think Buck got it backwards, I-90 is preferable to I-94, and that would pretty much preclude you going "over the top" to Soo. Besides, didn't you say you will be returning home through Canada?
You can avoid the Buffalo, Cleveland, and Detroit traffic if you take 401/402 to the border and cross at Sarnia. You can avoid the bulk of the Chicago traffic and a bunch of tolls if you stay on I-80 to Omaha and take I-29 to I-90.
You can always take the Tsawwassen ferry on your return trip.