I am traveling to Duluth in mid-August. I would like to take off a couple of extra days to do some sight-seeing, but I'm not sure how many days I'd need. Also, I probably wouldn't take off any more than 2 days, plus the weekend day I have before my conference starts. So, I'm looking at renting a car for a day or two to drive to Thunder Bay and/or International Falls. Can anyone give me advice as to which is a better destination, as well as how much time I would also need to see a few things in Duluth?