Hi Katrina,
You will have such a wonderful vacation this summer with all your Grandchildren! May is a great time to bring the family. The weather is fantastic with highs in the upper 80s and lows in the upper 60s. I am not sure if you are staying on Walt Disney World property so I picked the parks based on if they had Extra Magic Hours available for the day. I will list the day and park as well as the Quick Service Restaurant!
May 25th- Animal Kingdom- Restaurantosaurus or Flame Tree Barbecue
May 26th- Magic Kingdom- Be Our Guest Restaurant (for lunch)
May 27th- Hollywood Studios- ABC Commissary
May 28th- Epcot- Sunshine Seasons
May 29th-water park or favorite theme park
May 30th- Magic Kingdom- Pinocchio Village Haus
Please let me know if I can help with further with your planning! I know your vacation will be just Magical, Katrina!