The #1 thing for me at Costco is the gas. I have the credit card, so I get 5% cash back on the first $7,000 of gas I purchase in a year. Being as that, as of now I am spending ~$70/week on fuel, I will not hit the max for the year.

But 5% cash back on ($70*52=)$3640 means I get $182/yr by default back to cover the $130 annual cost of the executive membership. Doesn't sound like a good deal until you also factor in that their fuel is typically 10 cents a gallon or more cheaper than the next least expensive fuel place, which means that for my roughly 650 gallons of fuel a year baseline costco gas saves me an additional $65.

So yeah, nothing really amazing, but the fact that having the membership lets me pocket something in the neighborhood of $120/yr on top of the occasional shopping trip and access is nice.

There are so many people like you (who only use it for gas) that they are now building Costco gas stations not attached to a warehouse. Massive stations like the ones near the warehouses.

They also use "Top Tier+" gas.