Hello, Linda!
I think it's so wonderful that you will have the opportunity to bring your sweet granddaughters along on your Walt Disney World vacation. I'm sure you will all make many magical memories together this October. All four of the Disney theme parks are appropriate for all age levels and interests, but I do think your young granddaughters will enjoy Magic Kingdom Park and Epcot the most, followed by Disney's Animal Kingdom Theme Park and Disney's Hollywood Studios. If your trip is for three days, you may want to spend two days at Magic Kingdom and one day at Epcot to really explore all that there is to do at these fantastic theme parks. One of my daughter's favorite activities at Epcot is to visit with her Disney Princess friends in their own 'lands' around World Showcase. I bet your little princesses will have a wonderful time twirling and posing with their favorite Disney Princess friends, too.
You mentioned that your trip is only 100 days away, and while many of the more popular
character dining restaurants may not currently have any availability, I'd like to encourage you to keep checking back. Many guests overbook dining reservations up front and then cancel them before vacation time, which can really open up reservation times and locations. You can check online on the Disney dining page for the dates and times that you are hoping for, and who knows? You just might find that coveted reservation at Cinderella's Royal Table, Akershus Royal Banquet Hall, or any of the other delicious dining options that you have planned. It does help to check back often!
I hope you have a magical Walt Disney World vacation, Linda! If you have any other questions before your visit, please do not hesitate to stop back by the Moms Panel. Happy planning!