Costco – to shop or not to shop, that is my question…

We have been without a Costco membership for several years, which surprises most people. Having kids = membership, to most.
We have been toying with the idea of renewing our membership.
For those of you who are regular Costco shoppers, what things to you purchase there on a regular basis that you find are a good deal? Any items to stay clear of?
I went with a friend recently and found good deals on:

10 lb. C&H sugar (~$5 vs $7.50 at my store)
Powdered sugar (4 lbs for my normal price for 2 lbs.)