If you like buying in bulk, then Costco is perfect for you. This warehouse is huge, with huge variety of items available. I think I've been here probably about 50 times, and have seen different items in stock each time I've been here.
The only reason I'm not rating this place very high is that the line crowding is horrendous, especially on weekends. It also doesn't help that with the way the store is set up, the psychological effect causes many customers to lineup in the left half of the cashiers, while the right half has relatively less people. I generally don't mind crowding (I'm Asian after all), but if it can be avoided, then that's an issue.
Funny thing is, in all the times I've been here I've never eaten at their small food outlet behind the cashiers. Perhaps I'll try one day.