We use Costco quite a bit for bulk items, on top of that we use the Costco AMEX card for damn near everything we can. I pay the full bill at the end of the month, and then each year in February we get both a rebate check from Costco and a separate one from AMEX that is always much higher than the $100 we pay for membership. It was especially useful when we bought our flooring and some other items for our rental home there.
As we learn to spend less on "stuff" (and we don't have that far to go actually, our low hanging fruit is to drive less and eat out less, not cut back on stuff) that may be offset some going forward, but given how many of our groceries and household staples come from there it should still be a good value.
Lastly, I was surprised to learn how much effort Costco puts into building up their "Kirkland brand" not as a generic, but a high quality alternative. I bought a few pairs of Kirkland jeans last year and they have been some of the most comfortable and durable I've owned.
