Hi Tabitha,
Guests with dining reservations at Disney Resort hotels (other than their own), are permitted to park I the parking lots at each of the various hotels for a period of up to 3 hours whilst they enjoy their meal. Unfortunately, it therefore won't be possible for you to leave your car there once you have eaten your breakfast, whilst you visit one of the theme parks.
You have three options as far as transportation goes:-
1/ Drive to Disney's Grand Floridian Resort & Spa and Disney's Contemporary Resort for your breakfast reservations and then once you have finished, drive to the parking lot for the theme park which you wish to visit.
2/ Drive to the Transportation & Ticket Center where you can park your car for the day. Take a
monorail from the Transportation & Ticket Center to Disney's Grand Floridian Resort & Spa and Disney's Contemporary Resort and then once you have finished your breakfast, you can take the monorail to either the Magic Kingdom Park or Epcot.
3/ Take
Disney's complimentary bus service from your Resort hotel to the Magic Kingdom Park and from there, take the monorail to Disney's Grand Floridian Resort and Spa and Disney's Contemporary Resort for your breakfast reservations. Once you have finished your breakfast, you can then take the monorail to either Disney's Magic Kingdom Park or Epcot.
The
Transportation - Frequently Asked Questions section of the Walt Disney World website may also be useful when planning your trip.
Wishing you a magical trip filled with memories which will last a lifetime!
Emma