Hi Marian,
This is a fantastic plan. I think you should bus to Magic Kingdom but then take the monorail to the Magic Kingdom resorts. '
Ohana, 1900 Park Fare, or Chef Mickey's would be my top choices for your family. A quick online search shows 'Ohana has availability for August 12th. I would be sure to book an Advance Dining Reservation now as these locations will book up as the dates approach. You can click the link above or give Disney Dining a call at 407-939-3463.
Another fun alternative is to take a boat from the front of Magic Kingdom over to Disney's Wilderness Lodge. Here, you'll find Whispering Canyon Cafe, a rootin' tootin' good time to commemorate your first evening at Walt Disney World.
The ambiance of each of the Magic Kingdom Resort Hotels will undoubtedly start your vacation off magically! All of the transportation options mentioned are complimentary to you. At the conclusion of your meal, take the transportation back to the Magic Kingdom and you'll see a bus stop headed for Art of Animation. Buses will run for about an hour after the park closes. You will not need theme park admission unless you actually enter the Magic Kingdom.
I'm excited for you, Marian, and please feel free to visit me again with follow up questions.
Best wishes,
Sherri