My favorite way to save at Costco is by buying gift cards.
I stocked up on Fleming's Prime Steakhouse & Wine Bar gift cards the last time they offered $100 in gift cards for $80. I can't tell you how many happy hour dates we've gone on thanks to Costco.
We've bought California Pizza Kitchen, Roy's Hawaiian Fusion and Einstein Bagel gift cards, too. The restaurants rotate, so you don't always find what you want, but there's always a deal. I stretch those dollars more with coupons or using during happy hour. Who doesn't love drinks and appetizers for cheap?
I also love the discounted movie passes. It's great for when friends want to get together for a movie and dinner. I'm not big on paying more than matinee prices. So this keeps me from totally seeming cheap and saying no to the movie. I'm just dollar smart now.
Lately, I've been buying attraction tickets. I've found great deals on Universal Studios Hollywood, a local water park, ski tickets and baseball games. I'm always smiling when I use them because I don't ever pay full price. However, I will say that I do check on online deals before I buy, just to make sure I can't get the tickets from a reputable source for less.
Cheers!