Depending on what time of the day you're attempting this, you're looking at a 4.5-5.5 hour trek from DTW to YYZ. The big unknown is the border crossing wait. I-94 from DTW to the bridge or tunnel moves fairly well if not during rush hour. And the 401 from Windsor to/from YYZ moves fairly well also, again if not during rush hour.

I would not recommend doing the Port Huron route from DTW-it just doesn't make a lot of sense time wise. IF you were starting/ending out in the northern burbs of Detroit, then absolutely go that way.

The prob w/ BUF is the lack of options, and cost of airfare.

Don't forget your passport....