I love new people, they resurrect old threads!
To continue my Costco love:
Environmentally responsible dish soap, this stuff is the best, especially for Cast Iron cookware
Charmin Ultra Soft, cheapest anywhere
Sabatino Tartufi truffle zest and truffle salt. I love these on burgers
Better than Bouillon Beef Base
As others have mentioned, their cheddar cheese is excellent. I also recommend Kirkland Brie and Kirkland Bleu Cheese.
I buy their fresh-caught salmon, but only because it's cheaper and easier for me to buy there than the fishmonger. I've had better quality salmon, but Kirkland's is not bad.
Ditto on the scallops, they are not dry-packed, but they taste ok and are cheaper.
I used to buy their chocolate chip cookies, but it would take me days to eat them, so I stopped. I like their crispy ones better than their cakey ones.