Hi Tammy!
I understand how much the kids (and even the adults) will need to stretch their legs after that long drive to Walt Disney World!
When you arrive, you should have time to check in, and even freshen up. Then, how about heading over to Epcot for a great dinner? With so many great table service and counter service restaurants at Epcot, it should make it easy to appeal to the whole family, and maybe exactly what everyone needs to refuel from the long trip. Follow up dinner with a viewing of Illuminations at 9pm, and I think you're off to an awesome magical vacation! With the park closing following Illuminations, you'll probably find yourselves ready for a restful nights sleep, looking forward to playing in the parks the next day.
However, be flexible. Sometimes, 6pm turns a bit later all too soon. If you find yourself needing a plan B, your resort has a playground where the kids can let off some steam, and plenty of "icons" to explore, not to mention great photo ops!
The Boardwalk also has great restaurants, and fun (but more leisurely) activities the family can enjoy. Downtown Disney features even more dining options, and maybe you'll enjoy a tethered balloon flight,
Characters in Flight, with panoramic views of the Walt Disney World Resort to get everyone even more excited!
I hope this helps. Come back to the Moms Panel if you would like any more assistance with your magical vacation planning!