I have only just seen this post, and I suspect that you have already been down. If not, I hope this helps.
If you and your partner like to eat well, then a meal plan definitely makes sense, as your 8 year old we be able to eat free. The $50 meal plan is definitely not worth it, as you are limited to 2 restaurants. That being said, Marketplace is very good, so that may be enough for you. The more expensive meal plan would be worth it if the adults can eat that much food. Dinner can easily be $80+ per person and up plus gratuity. However, it is a lot of food. When we go to Mesa Grille, we often share our entree, and if not, I end up bringing half of mine home. Rarely do we have dessert.
Hope that helps!