Well, if you have a rental car and want to eat off site, then a good idea is to visit a grocery store when you arrive, buy a styrofoam cooler, and stock it. That way you can have doughnuts, snacks, and drinks for a couple meals in your hotel room.
Even though the parks open at 9am, you still wanna be in the parking garage by 8am, because it takes a good 15 minutes to walk to the gate. You wanna be there when the park opens at 08:45am.
There are many places along International Drive if you do want to eat offsite in the morning.
Me? I drive up, stay offsite in cheap hotels. I bring a cooler with some beers in it, a few snacks, and a bottle of rum. That saves me money on the drinks. From previous conversations, it's the drink prices that get everyone bummed. Most don't mind eating at the restaurants. So if anything, do the cooler to save on drinks.