Hi, Kirsten!
What a wonderful trip for your two little princesses!
First, to get an idea of what to expect for the littler one, take a look at this really useful post "
Little Ones at Disney Theme Parks." There, you'll find lots of information about traveling with the youngest Guests; that will help you understand how many of these options will be perfect for your older daughter, too. You can add experiences as you have time to do so, and as your daughters' interests dictate.
For example, at those ages, I suggest dining at
Cinderella's Royal Table in Magic Kingdom or at
Akershus Royal Banquet Hall, in Epcot's Norway Pavilion. Either one of these will provide your family with priceless memories of dining in royal fashion, with visits from some of your favorite Disney Princesses, too!
I also suggest that you set aside a portion of a day to visit
New Fantasyland in Magic Kingdom. There, you'll find some of the newest "immersive enchantment" throughout all of Walt Disney World! A meal at
Be Our Guest Restaurant (Quick Service during lunch hours need no reservations. Table Service during dinner hours will require reservations made as soon as possible; this restaurant is one of the most popular on property, so it may book up 180 days in advance of Guests' check-in.)
Send more questions as you think of them, Kirsten! I'd love to help you plan that perfect trip for your princesses!