You really have three options -- the
DVC discount, the DDE, and the
DDP.
The DVC discount gives you 10% off of covered items at participating restaurants. It's a free member benefit, and is good until DVC decides to no longer offer it.
The DDE gives you 20% off, including alcoholic beverages, for up to 10 people at a meal, provided they're all dining together and on the same check. You can also use DDE for alcohol purchases on other plans -- DDP, for example. DDE is the only discount that applies to alcoholic beverages. DDE does not include any tax or tip. It is good for about 13 months from purchase, so it can be used on multiple trips.
The
Disney Dining Plan costs $37.99 per day for adults (10 and up) and $10.99 for kids 3-9. In 2007, the kids price remains the same and the adult price goes up $1. The DDP gives each person one Table Service, one Counter Service, and one Snack for each night of the stay. You pay for it at checkin, and it becomes effective as soon as you pay for it. It expires at midnight after checkout. DDP includes ALL taxes and an 18% gratuity on each TS meal.
DDP can be purchased on any DVC points stay, without additional park tickets you don't need. DDP must be purchased for the entire length of your stay, for every member of your party.
You really have to look at the composition of your party, your normal eating habits at WDW, and the details of each plan to see which works best for you.