When traveling to Duluth, most of the activities somehow center around Canal Park. You can get a hotel right on the water and walk to the restaurants and shops.
The Maritime Museum right on the canal offers a great history of the area as well as the ship schedules. Its a great place to be when the ships are coming through the canal.
Having said that, don't miss other things Duluth has to offer. Many people travel to Duluth and never leave Canal Park.