The wait times at the Bluewater Bridge in Sarnia are always bad on Monday's and Tuesday's with the transport trucks backed up - so it you're going on those days I'd figure that into the travel time (it's probably the case with Windsor as well). Other than that, the waits aren't too bad anymore. There are separate truck lanes now. I don't know about going Windsor - Detroit, we have only done Sarnia - Detroit, but traffic can get quite heavy going into Detroit at rush hour - 3 pm - 6 pm. Try using expedia maps and getting routes going both ways to a point beyond Detroit. There is a time listed on the route and see which is quicker. The time is usually always longer than in real life, but it will give you an idea if one way is quicker than the other for your route. Also, if you happen to be a member of CAA they can advise you on the quickest route.