Are you on a budget? If you are on a budget do breakfast because it is less expensive and those buffets are expensive at dinner.
If you are on the dining plan do dinner at Crystal Palace. I would pay OOP for Chef Mickey's breakfast and then still do a dinner that night. Chef Mickey's was good, they had a LOT of variety, plus it is easier to start at a hotel earlier in the morning then head to the parks as opposed to go to the park head to Contemporary then back to park.