I used Costco on our first cruise, and have booked through them again for our next cruise, next summer. The savings are TREMENDOUS if you book early, and we were obviously VERY happy, or else we wouldn't have used them again. Slindamood had a bad experience, but I think that is very rare. It's always possible you can have a bad experience no matter WHO you use, but the norm is Costco is a great company to book through.