I like the mini-golf idea.
I also think there are a few restaurants that my kids loved at that age. Cowfish, for example---bento boxes with sliders and sushu, what's not to love!
I think you could make a full day at City Walk: an afternoon matinee at the theater there, dinner at Cowfish, and mini golf after. This has the bonus that no one has to get up early---a huge win at that age.