Vegetables in bulk are a godsend if you go through them like we do. It feels weird buying vegetables from Costco but they have a high turnover and they're always super fresh.
My other costco favourites are the book section and the dry goods aisles. Soooo much good stuff. Cereal, canned goods, baking supplies - all are better in bulk. They have a great selection of fresh foods too.
I also buy all my lady's razors here because buying a bulk pack of fifteen razor heads is twice the cost of what a pack of four would cost in any other store.
I'm pretty sure costcoitis is an actual disease, because the first thing most of my friends did when they moved out was buy a costco membership. There is tons of great stuff - if you have room for it.
I don't feel that the store is that badly laid out - it feels very sequential - electronics, household appliances, etc. And the fact that the layout is nearly identical in every store means that once you've figured out where something is, you can find it again no matter what province you're in.
I like to go before I've eaten and stock up on samples - I've made a few discoveries of new favourites that way. If they're running low, then I grab one of the hands down best Hot Dogs in the city from their little restaurant thing ($1.99 gets you an HD and a drink. Not bad). Actually, all the food from that takeout window is really good.