big difference between the two is: I managed to get ADR's for CP, but CM is gone. (and I am going the first week in june.)
another big difference is, you need to enter a park to get to CP. unless I was planning to be in the park that day, I'd head to CM if possible.
as for cape may cafe, last i looked up about it, the characters are only minnie, goofy and donald. so if you are looking for Mickey, you'd be out of luck. (which I am.

)
Since you are going for breakfast, well, my view is, you can't really mess up basic breakfast foods... so I usually dont worry about it.
the following is copy and pasted from WDWinfo.com
Goofy's Beach Club Adult Character Breakfast Buffet 7:30am-11:00am - Fresh cantaloupe, honeydew melon, watermelon, and fresh berries, mixed fruit and yogurt selections. Scrambled eggs, omelets and eggs to order, biscuits and gravy, French toast, and Mickey waffles, bacon and sausage, seasoned potatoes, assorted hot & cold cereals, bread pudding with vanilla sauce, muffins, danish, and donuts. Bagels and breads toasted to order, coffee, tea and juice selections. - $20.99 *
[chef mickey's] Breakfast Buffet: Guests 10 & over (7:00 am - 11:30 am) - Premium Fruit Bar: Seasonal melon and fresh fruit display, assorted flavored yogurts and more. Cereal Selections: Almond granola, Frosted Flakes, Fruit Loops, Cocoa Krispies, hot oatmeal and grits. Breakfast Specialties: scrambled eggs, Pluto's cheese blintz, 3 cheese omelet, Chef's daily omelet, Corned Beef hash with cornbread, Goofy's veggie lasagna, Mickey waffles, cheese potatoes with bacon, Breakfast potatoes, bacon & sausage links, Minnie's breakfast pizza, Challah French toast, pancakes with a variety of toppings, and buttermilk biscuits with country gravy. Pastry Chef's Creations: bagels, chocolate croissants, muffins, cinnamon rolls, Rice Krispie treats, peach cobbler, warm bread pudding, assorted danishes and more. Traditional breakfast beverages included. - $26.62 *