Wanted to contribute to this thread now that I can speak from experience. Hope this helps those who have posted, and especially the OP.
We are midway through a two week vacation on the dining plan and I thought I might offer some commentary. We are a family of six, our kids ages 18, 15, 11, and 7; three boys and the last a girl.
The dining plan was quite expensive for us, but has been worth it thus far.
There are a wide array of snacks available and we have all enjoyed the snacks randomly through the vacation. We havent gone into the parks every day so we havent run short on snack credits and it doesnt look like we will. It has been fun to indulge this kids a bit, and just say "no problem" to the requests for popcorn, ice cream, etc.
The counter service meal credits are simple to use and the food is plentiful, because they include a main dish and either a dessert or side dish or salad, depending on the place, plus beverage.
We have very much enjoyed numerous table service meals that we have always wanted to try but were too expensive for us. We have also tried several restaurants to which we have only gone to lunch in the past due to expense and have gone there for dinner this vacation instead. It has been an indulgence in a good way for the kids to get beverages at meals, and several restaurants have allowed specialty drinks which we have all enjoyed (smoothies, etc.)
My biggest concern was that there would be too much food for us, and that has been the case somewhat, because we have a tweener. That would be our 11 year old, who doesnt have an adult appetite, yet we had to pay full adult price for him.
We handled this through sharing meals, which has been no problem at all with any server. I have ordered meals that I know he will eat, and split the entree with him. Between my appetizer, half the entrée and the desert, I have had plenty of food, and the half portion has been enough for him. As a result, we have been able to save his table service credits and have enjoyed a few extra meals and / or signature meals with his credits. Of course that left us with a few extra meals worth of counter service, but the teenagers are available to take care of those.
By the way, my teenagers have polished off their meals most of the time. And our 7 year old has done fine with the child menu selections, which are actually pretty varied from restaurant to restaurant.
Over all, the plan has been a positive experience, but has required advanced planning for TS meals, and sticking to a schedule accordingly. We have enjoyed it, and will do it again, even though it is more expensive than what we normally pay for food here (we usually eat quite a bit in our DVC room.) My wife has loved the vacation from meal prep and dishes as well.
We will do the dining plan again next time. For us it has made for a more memorable vacation and a much more pleasant dining experience for all of us. I would recommend trying to find the funds and give it a try. However, if you have more than one "tweener" (an "adult" aged child that still only has a child appetite) I would be careful, because it will probably be too much food and you'll wind up leaving dining credits when you depart or throwing away a lot of perfectly good food.
If anyone has specific questions, please feel free to ask. However, I won't be back on line until this weekend.