From my experience dealing w/the Travel Agents, and Carnival themselves... the past guest discounts are only particular cruises and particular dates. It seems as though the spring/summer cruises RARELY offer any past guest discounts. You can go into the carnival website and look under "specials", then "past guest" offers to check to see what's coming up. Even when they advertised recently that "virtually every summer cruise" had the past guest discounts, the dates I wanted in mid-july or early august were NOT available. Kind of a bummer, I know. I had originally thought that you'd get a discount on any cruise you wanted, since you were a past guest.... NOT so. I've also rebooked another cruise using one of the internet agencies that was much cheaper than going thorugh a "bricks/mortar" TA. Good luck!