It’s been a while since I’ve done business trips to Detroit but I spent way too much time there. Windsor is a nice visit for some food. This time of year, Ann Arbor if there isn’t a college game, is a nice town with restaurants and bars and a nice downtown. Same with Royal Oak and Birmingham on the north side. I always stayed out in Plymouth, so I found a great place to run, and some nice restaurants there.
I never spent much time downtown. I guess it all depends upon where you are staying..
If you’re a car person, Dearborn and the Henry Ford Museum are great places.
Toronto is not too far for a long weekend, but it’s just far enough to be a bit of a road trip.