While I haven't tried the dining plan yet, I am quite sure we are going to try it in January. However, my kids are 12 and 6 - so I will need to get 3 adult plans and one child plan.
Our goal is to have least one meal where my DH and I will have a nice evening dinner at a Signature restaurant - thus using up 4 TS credits for one meal. We will get the kids CS meals that night and either get a sitter for them or have them go to the kids club. If that works, we may even try that again - thus not subjecting the kids to long sit downs every night and giving us some adult time.
And just so I don't get flamed for using children's credits on an adult meal - I won't be. I will make this up another day by sharing a meal with my 12 year old (who needs an adult package - but eats like one too!) at someplace like ESPN on the Boardwalk. That way, we would only use 1 TS credit for two of us. The appetizers are SO huge there, they are big enough for a meal anyway. And, if we run out of TS credits, I can always buy a CS meal someplace - right?
So - you can make it work and the price for kids is reasonable enough. I can't get my daughter a CS meal for under $6 at Disney anyway (when you include a drink and a dessert) and then she will get a snack credit (and she loves her snacks!)- so basically that covers the price of her plan and TS will then be a bonus - almost free.
If the kids get antsy at a sit down restaurant, box it up and take it back to your room. We have done that many times... maybe not quite as nice, but better than cooking- in my opinion anyway!
Good luck with your planning. Only you know what will work best for your family - but the opinions of people who have tried it always helps - right?