If your fussy 6 yo will eat waffles, fruit, scrambled eggs, sausage or bacon, I'd definitely recommend the Best friends character breakfast at Ohana. My DS6 is a big breakfast person and he absolutely loved Ohana with Mickey, Pluto, Lilo and Stitch. It was probably his favorite meal of the whole week. It's very relaxed too for a character meal, not nearly as loud as another one we went to earlier in the week.
They bring a fruit plate to your table, your drinks of course and then start bringing skillets filled with scrambled eggs, bacon, sausage links, potatoes and mickey waffles. It's all you can eat and your server will bring whatever you need. It was a great breakfast experience and each character spent a lot of time at every table while we were there. One of the best things we did all week and something we'd definitely do again.
Other suggestions: the buffets like they mentioned usually have chicken tenders, mac & cheese, etc. We did Hollywood and Vine and DS6 was fine there. Have also heard great things about Whispering Canyon and Boma. But we didn't try either one.