Hi William! I can totally see why you're so excited! It's so fun to plan your first Disney vacation! Note that characters can change, and none are guaranteed.
Chef Mickey's in the Contemporary Resort is a yummy buffet. There's a great variety to choose from, so even the pickiest of eaters will be happy. Typically, we see Mickey, Minnie, Pluto, Donald and Goofy.
The
Garden Grill is located in the Land Pavillion in Epcot. Food is served family style and is all you care to eat. What I love about it is the restaurant slowly rotates, where you actually see part of the Land ride. Chip and Dale are the hosts, and we've also seen Mickey and Pluto. They're all dressed up in their farming outfits, and are so fun! This would be my first choice between the two. The setting is cool, the character interaction fantastic as is the food.
Hope this helps with your decision-making William!