Eugene-
Welcome back to the Disney Parks Moms Panel. I love that you are making this trip with your grandkids. You are going to have a spectacular time.
We always plan ahead by making
Advanced Dining Reservations (407-WDW-DINE or 407-939-3463) to ensure we get the restaurants we want for the number of people in our party. The difference between staying on and off property differs in how far out you can book reservations and for how many consecutive days.
Guests staying on property with a valid reservation number may book advanced dining reservations 180 days before their check-in date for up to 10 days of their Walt Disney World Vacation for a total of 190 days in advance. This is a tremendous advantage in securing hard to book reservations like Cinderella's Royal Table and Chef Mickey's. A tip would be to book those later in your trip since there will be less competition.
Guests staying off property may book 180 days in advance of each individual day. This means that you will be able to book Day 1 of your dining reservations 180 days in advance, then wait till the next day to book Day 2 and so on.
If you all plan to eat together then I would suggest you make reservations for everyone in your party beginning at the 180 day mark. Should the off property Guests want to eat at different restaurants they will need to wait until they are 180 days out and call daily.
I hope this helps you coordinate some amazingly delicious magical meals together. Bon appetit!
Enjoy making many Magical Memories!
~Jason °O°