I'm in the middle of my second grand gathering (we arrive at WDW on Sept. 28th with a group of 19) and have found the grand gathering agents very helpful. There is no discount booking a grand gathering, but you are eligible for "experiences" that are not open to the general public, like the grand gatherings fireworks cruise, a special breakfast at Tony's etc. Basically what they do is give you a gathering number that "links" all of your reservations together so that when you call to make reservations for things like dining or activities, it pulls up everyone in the group at once, making it easier to book. The number to call is the same 1-800-828-0228 and one of the prompts will ask if you have a party of 8 or more. Good luck and happy planning!