Well, I have roughly the same mix of people. So instead of telling you to do the math, let me do the math for you. These numbers are all estimates, but they are close enough to make the point.
Stay & Play Free... 2 kids tickets approx $220 each.. total saving $440.
Free Dining 6 days ... $34.99 for the adults (69.98 total) and 11.99 for the kids (23.98) = $93.96 per night savings x 6 = $563.76 savings.
On the surface it looks cheaper to use the free dining. Some would say that they can do food cheaper themselves. If that's the case then you need to plan out your QS meals using the dis menus and see if you can pay cash for the meals and beat the free ticket price.
Let me show you what I mean....
Taking 3 things into account to check the value of any discount (Room, tickets and food) We will disregard room, since in this case the amount will be the same no matter which way you go.
Example 1 (free dining)
Tickets $950 (approx)
Food $0
Example 2 (Stay and play)
Tickets ... $500
Food $450 cash or $75 per day total
So if you can spend less than $75 per day in QS food, then stay and play is your best bet. The more days you stay the better the FD value is. The savings go up $93 per day, but ticket savings increases only about $10 per day.
In my case we are staying 7 days, currently on kids stay/play and paying for QS dining, but I am hoping for free dining. The saving/cost of not being on the plan is so small, that the convenience factor of having is all pre-paid and done is well worth it. I don't want to have to be worrying about budget and controlling spending every time I want a snack or meal.
One more thing to note... if you are going during Food and Wine, the snack credits become a HUGE!!!!! Value. Instead of $3 popcorn, you can use them on $5 and up items at the food and wine booths. We figure with 56 snack credits, we plan to use approx 20 of them at food and wine. So if we get the FD package we are going to call it snacking around the world for free.