For non-character meal, I would choose Kona Café at the Poly resort. Very speedy service (but very friendly) and wonderful breakfast menu. I'd pick this over Crystal Palace for breakfast, inside MK - unless the kids are big Pooh and Tigger fans.
For MK character meals, I would instead pick Ohanna with Mickey and Stitch, or 1900 Park Fare with Alice in Wonderland and Mary Poppins. Ohanna is family style, and 1900 park fare is an excellent buffet.
If you choose an Epcot resort restaurant for breakfast, you would want to park with their valet parking. This way, you could stay there all day, and not have to move after breakfast to the Epcot lot. Cape May at Beach Club has a Mickey and Minnie character buffet that is MUCH MUCH MUCH better than Chef Mickey at the Contemporary.
For DHS, Hollywood and Vine is your best bet. You could do the Cape May or other Epcot resort restaurant, though, and take the boat from there to DHS.
For Animal Kingdom, AKL restaurants have rave reviews, though I've never had their breakfasts. Tusker house buffet is also a very good option, with Mickey and Donald in safari gear. The buffet has African themed options, in addition to "standard" choices, and is great.