I really only use my 2500hd for towing and hauling my atvs and home improvement projects. On weeks that I am not needing to haul anything I try to drive it at least once a week so it gets exercised by making a trip to the grocery store.
I personally would be comfortable hauling up to 2000 lbs and towing about 7700 lbs with most half tons. This will cover the hauling and towing needs of most truck owners.