Pat mentioned in the first post that accommodations can get filled-up in the summer. I have found that to be true myself. Here are a few suggestions.
The Voyageur Lakewalk Inn is an old-school family run motel that doesn't pop-up on all of the hotel search sites. It's nothing fancy, but the location is great. It's 3 miles from Northland on the same street (Superior). And it's a block from the historic Fitger's Brewery complex which now holds an inn, bars, restaurants, liquor store etc. Always nice to be able to walk to get a drink.
http://voyageurlakewalkinn.com/http://fitgers.com/If you belong to a club of some sort, the Kitchi Gammi Club might be a good option.
http://kitchigammiclub.com/Of the above, I have only stayed at the Voyageur and that's where I will reside for this trip.
Regarding car travel to Duluth, it could very likely take a half hour or so longer than what your phone is telling you now. Duluth and the surrounding communities is vacation land for many folks. Expect that the Thursday and Friday afternoon and evening commutes will take longer. Saturday morning might not be too slow.