Hiya Camille!
Welcome to planDisney! Your granddaughters are so lucky to have you as their grandparent! I sure am excited to help you out with your question as I have a ton of experience with my little ones! Since that day Walt Disney watched his kids ride on the merry-go-round in Griffith Park and thought of making a park where adults and kids can enjoy it together, all Walt Disney Parks have so many experiences where the littlest little ones and the biggest kid at heart can enjoy it together.
The best way to pick out the best
Attractions and Entertainment for you and your granddaughters is to filter by Park on the top and then click "All Filters" and select "Age" as "Preschoolers". You can even set it by height so you can make sure that it is accessible to them. You will then find a list of all the things they can do with even more descriptors on them such as "slow rides" or "spinning".
Some suggestions for you:
I find the best Park for little ones to be
Magic Kingdom Park. There are so many rides you can enjoy together, especially in Fantasyland. My favorite experiences are "it's a small world", Peter Pan's Flight, The Many Adventures of Winnie the Pooh, and Dumbo the Flying Elephant. You can also meet some fun characters such as Ariel, and my favorite guy Mickey who can you meet at Town Square Theater!
EPCOT is also a fun experience, especially during Festival times. Right now until the end of June, there is the
International Flower & Garden Festival with delicious food and drinks for the grown-ups and fun playgrounds and gardens for the kids to play and see. The World Showcase area has the Gran Fiesta Tour Starring the Three Caballeros in Mexico and if they are little Frozen fans then they should check out Frozen Ever After in the Norway pavilion. A fun hidden spot is the small children's hedge maze in the United Kingdom pavilion. It's perfect for tiny people to run around and explore.
Kids will get tired no matter where they are and there is something to say about getting tired in Walt Disney World. It can be such an exciting place and a sensory explosion. Naps are crucial and you should know your grandchildren's temperaments. If they are flexible "nap anywhere" kids who can take a power nap in the stroller then you can stay in the Parks and roam around with a nice grown-up drink. However, if they are the kind that needs a dark room with silence then going back to your hotel room is important. You are allowed to leave the Parks and return later in the day and I strongly suggest this! Staying on-site at a
Walt Disney World Resort makes that easy as it's a short ride away from each of the Parks.
I must make sure you know about the
Baby Care Centers located in each of the Parks. They are these havens in the Parks with quiet and family-friendly spaces with private feeding rooms with comfy chairs, kid-sized toilets for that newly potty-trained child, a kitchen with microwave and sink, and a baby shop with formula, baby food, diapers, and wipes. I have visited every single one with my little ones and it's a great nap spot.
I hope this helps and that you have a magical time with your granddaughters at Walt Disney World Resort! See ya real soon!
-Nimmy