Yvonne, welcome aboard! Wow! You are taking on a big event. 325 people, ready to have fun together as they set sail on one of Disney's pixie-dusted ships! You can certainly be sure that Disney Cruise Line is the right choice, as they have activities and events for everyone's individual tastes, as well as their families from babies to our most senior cruisers!
While there isn't a group sales office to call, you can still book this together. Disney suggests that you get an idea of how many guests you will have and then give them a call. Please be ready to tell them the number of adults and children and their ages, per stateroom. Some staterooms can accommodate three to four guests, while others can accommodate up to five.
If you choose to add a few days at Walt Disney World before or after your cruise, you can certainly book this all together through Disney Cruise Line. However, if you want to include the Dining Plan or any specific Walt Disney World promotions, you'll need to book those reservations separately through Walt Disney World.
I think the best place to begin is to take a look at the
Disney Dream. You mentioned you'd like to sail for a three or four night cruise in June of 2014. The Dream is the ship that will offer that type of itinerary for you during that month. Then give Disney Cruise Line a call to begin the specifics. You might also consider contacting a travel agent that specializes in Disney cruise vacations, as they might be able to take a lot of the work off your hands, which I am sure you would appreciate when taking on such a big adventure!
Good luck planning what is sure to be a very magical cruise for your former classmates! Please let me know if you have any other questions as you continue planning!