Sharon,
Funny that you mention Costco's roasted chickens because I have a friend who is obsessed with their roasted chickens. He eats them 2 or 3 times a week. Gets 2 meals out of it and freezes the bones for soups. He told me he slathers the chickens with some kind of Portuguese hot sauce and then reheats them on his grill. As a matter of interest this friend has Crohn's Disease.
I occasionally buy those roasted chickens at my local supermarket which does a fairly good job with them.
I also make soup out of the carcass that is left after the chicken is consumed. Usually I will leave a little meat for the soup as well. My local supermarket sells packages of fresh soup greens, consisting of a parsnip, a turnip, an onion, celery, carrots and dill. It's sufficient for one large pot of chicken soup. I usually make some matzoh balls to go with the soup but you can also boil some egg noodles if you need to throw some carbs in there.