I love looking through the costcotravel.com website. I've never booked anything through them, but they have some amazing prices. We always use the costco codes to book cars when travelling, and they are always better deals then regular codes.
We plan on using Costco for a trip in November. If you book an all-inclusive, you cannot book online if you plan on travelling through Canada. But, if you call them, they will arrange a flight from Canada.
Love that site!