We've been Sam's members for a few years now, and on a whim we tried out Costco. We are now believers. Costco has a MUCH better selection of goods, and a wider variety of items, as well.
I've never in my life seen a wholesale club handing out sushi samples until this day - and it was a wonderful day! We are juicers and were able to get a full week's worth of fruits & veggies plus some other household stuff for less than $50!! - plus you get that 2% cash back at the end of the year. Heck yeah.