Most of the resort restaurants are very kid friendly - but they vary in terms of activities for kids.
Poly - 'Ohana is all you can eat skewers - for kids activities they have coconut races and hula hoop contests - allows the adults to actually eat & kids have fun. Since the activity occurs every hour - it can be hit or miss based on your timing
Kona Cafe has delicious food and is casual but has no kids activities. (does have a kids menu)
AKL - Boma - is all you can eat buffet - has a special kids buffet area - when we were here, there wasn't any kids activities so my boys were done way before we were ready to leave. (and the adults didn't want to leave!)
WL - Whispering Canyon Cafe - has regular menu/kids menu & all you can eat BBQ skillet; The draw of WCC is the interactions with your servers - if you are outgoing and enjoy some fun, you server may make you hats out of your napkins, bring you the largest tub of water you've ever seen, pepper your entire table with straws and just ask for some ketchup! You may be told to ride a wooden horse around the lobby, too. If your son is shy, you should let the server know in advance and you can just watch the "show."
50s Primetime at MGM is similar to WCC in the sense that your server controls how "fun" the interaction is. There you are served by "Aunts", "Uncles" and "Cousins" & "Mom" is the cook. Kids love it when the adults in your group are sent into the corner or have their vegetables brought out again as dessert.
My kids like the Teppanyaki restaurant in Epcot & the chef interactions - but to dh & I it is no better than our local Bisuteki & it cost more so we don't tend to go there.