Hiya Rachel!
Thank you so much for stopping by! Taking a rest day is always a great idea when traveling with little ones. We'd often do this with ours--a character meal, some relaxing around the resort, kicking around the pool.--taking it easy! Believe me, Mom and Dad sometimes need the break too!
Chef Mickey's is super easy to get to! You'll take the bus from Disney's All-Star Music Resort to Magic Kingdom Park. From there, you can board the resort monorail and exit at Disney's Contemporary Resort. From there you'll take the elevator (or escalator) downstairs to the 4th floor concourse.
You can also take the walking path from Magic Kingdom Park to Disney's Contemporary Resort. As you exit the bus terminal, you'll head toward the right (away from the park entrance) utilizing the path marked for Disney's Contemporary Resort. This is a great option if the kids are in a stroller, because you will need to cross the streets and pay attention to traffic (there are signals). It's a short walk, and we've made it tons of times with our kids. Once at Disney's Contemporary Resort, you'll head up to the 4th floor concourse.
For your return trip back to Disney's All-Star Music Resort, you'll just head back to the bus depot at Magic Kingdom Park and find your bus back to your resort.
Have a magical vacation!
Amanda