Hi Deborah,
We used the standard Disney Dining Plan this summer and carefully kept track of our dining costs, and in the end we saved over $200 (yea!). The cost of this plan does vary by dates, but basically it is $45.99/47.99 per night per adult (ages 10 and up) while it is $11.99/$12.99 per night per child (ages 3-9).
Prior to our arrival (and even before I made our dining reservations 180 days out), I had studied the menus of the table service restaurants available
here to study which ones we would get the most of our dollar from -- even going so far as having each family member place a pretend order to really getting a picture of our costs (www.allearsnet.com also has menus available, including counter service restaurants). You could do this to get an idea if the plan would be a worthwhile investment for you. You may also want to ask yourself how often you'd like an appetizer (not included) and do you want a dessert twice a day (included with lunch/dinner)?
From a budgeting perspective, it did helps us tremendously to have already paid for our food; we only needed to pay for gratuities. I also enjoyed not having to think about the prices of menu items when ordering, since we are often pretty frugal with our choices.
Thank you for visiting the Moms Panel; please let us know if we can help again.