You have plenty of choices Melissa, especially since you are traveling with such a large party. As long as 8 of the people in your group are over the age of 3, you will qualify as a Grand Gathering. Disney offers special events to these parties called
Grand Gathering Exclusive Experiences. Perhaps taking part in one of these events would be a great birthday celebration for your dad. To check availability and make a reservation, give the Grand Gathering travel planners a call at 407-939-7526.
If you'd like to have a cake made, Disney offers a special hotline you can call to place a custom order. Your choices with regard to size of the cake, flavor, and decorations are very extensive. I've seen pictures of some of the cakes other guests have dreamed up and the Disney bakers have done fabulous work. The number for the cake hotline is 407-827-2253.
Of course, you might also consider ordering a floral arrangement or gift basket and have it delivered to your dad. If you choose to go this route, I think you'll find that the Disney florist has a wide selection available including tins full of snacks, stuffed Mickeys, and various floral arrangements. You can give them a call at 407-827-3505 or visit them online to view some of your options at
www.disneyflorist.com.
Whatever you choose to do for your celebration, I'm sure your father's birthday will be magical. Have a great time!