As was mentioned, SLC and CVG don't have much O&D traffic. It's one thing to transit in those cities, but if you were in OZ and trying to get to one of the west coast cities, there would be little incentive to fly DL unless it was significantly cheaper. Personally, I think SLC is a better idea than CVG or ATL, but LAX seems the best choice as it has much better feed than HNL.