Hey there, Rachel!
My grandkids are similar ages to your children, and if I had one day to visit
Walt Disney World, I would be to take them to
Magic Kingdom Park. It's the most iconic of all the parks, and I think it has a perfect combination for the whole family. You'll find attractions for the thrill-seekers, like
Big Thunder Mountain Railroad, ones with familiar characters like
Buzz Lightyear's Space Ranger Spin, and ones perfect for littles, like
Dumbo the Flying Elephant ride.
Splurges you may want to make inside the park might include lunch at
Cinderella's Royal Table at Cinderella Castle, but I can't tell you for certain if characters will be back by the time you travel. I'd be more tempted to try and score a
Chef Mickey's table for either breakfast before the park or dinner after. You can take the monorail from the park over to
Disney's Contemporary Resort, where that restaurant is located.
The other splurge I'd do is definitely
Disney's Genie+ Service. Access to the Lightning Lanes will help with the wait times at the most popular attractions, and with just one day, it's worth the investment to do as much as you can.
Although tougher with little ones, if there's any chance at all you think you can wrap up the Magic Kingdom early, adding the
Park Hopper Option to your theme park tickets will allow you to hop to another park after 2 PM. If there are must-do attractions or a
dining experience you want to have at another park, this is a way to fit that in, too.
We are here to help, Rachel!
Anna