We shop at Reading (because we live in Reading), and though the first time we went I went crazy (DH is British, and wasn't familiar w/ Costco, so the total can come as a shock with so little in your cart).
Now we mainly get peanut butter, Red vines, brownie mix and dried fruits on each trip as our 'staples' from Costco.
I found it interesting what others bought lots of (like Ruffles and Tostidos) and wondered if you and your spouse were both American, because my spouse doesn't get excited about American products, so we don't always buy them (it's too much for one person).
I've seen Hersheys stuff at Costco, but refuse to pay so much for Hersheys! Though if they carried Reeses, I would buy a big box!