well, CS drinks are around $2, cookies the same, and an order of nachos supreme at Pop Century was $6.50. Mom's meal for the night, turkey dinner, 8.99.
There's $10+ (add tax) of your $35-38/ day that the plan will cost you. Kid's meals w/ drink and dessert = between $8 and $10 roughly. Their plan cost either $10 or $12, depending when you are going.
Snacks are things that are $2.50 or less, so that's up to $15 or so of your dining plan/day cost. Sit down's vary, but your average character meal is $22 per adult. So, if you are doing a sit down a day anyway, it definately is a good deal.
And we used 2 TS in one day, our CS for that day on another day.
Oh, and the basic meal plan (that I quoted the prices) is one TS (sitdown) meal, 1CS (fast food) meal and one snack. So unless you share (which believe me, is totally possible with this much food) it isn't 3 meals a day. I would NEVER pay extra for the extra meal, it would NOT be worth it. We couldn't eat it all as it was.
You could used half of your day's CS credits for breakfast, TS for lunch, and half of your CS credits for dinner, and probably still not use your snack or be hungry at any point in the day.
Have fun!