If you get a room upgrade the Park Inn by Radisson is very good, I prefer to stay there over any of the other Radisson properties in Oslo. I've not stayed in a hotel in Norway where breakfast isn't included on the room rate. The Plaza and Scandinavian are both pretty tired and badly in need of renovation, they are not worth the premium over the Park Inn, plus the Plaza is in a crappy part of town, if you like drug dealers and hookers it might appeal.