Their appliances have no extra/hidden fees for delivery, setup, and basic parts like the hoses for a washing machine. Some of the appliance stores near me advertise lower prices, but they add so many fees that it ends up more expensive.
They have a fantastic return policy.
Costco Travel have some great flight + hotel packages, all with extras of some sort (eg free breakfast, late checkout, waived parking or resort fee, Costco gift card, etc). I’ve gone on some trips where the flight + hotel package through Costco was cheaper than just booking the hotel by itself (essentially getting a free flight).
Where I live in California at least, Costco Gas is often at least $0.40/gallon cheaper than nearby gas stations.
Costco’s good even if you don’t need bulk stuff.