Ok, a few notes on restaurant tipping. My family owned a restaurant, and I'm quite familiar with how it all works, so hopefully this will help not only at Disney, but at any restaurant.
First, waiters/waitresses generally make an hourly rate that is FAR less than minimum wage. In Pennsylvania, their hourly rate is somewhere around $3. It is based on the assumption that they will be able to make up the difference in tips.
Second, in some restaurants, the waiter/waitress does not keep the entire tip amount. They pay out a portion to the bus person, runners, bartender, etc. since those persons also helped service you, either directly or indirectly.
Third, 15% is the standard amount in American full service restaurants for tipping. If you receive satisfactory service, this is the amount you should be tipping. It is based on the total amount of the food and beverage amount you ordered before any discounts, coupons, etc. The server does not set the prices... don't take it out on them.
Of course, if you received unsatisfactory service, then the tip should be adjusted accordingly. But be careful not to take out your anger with a mistake from the kitchen, which is not the fault of the waitstaff, on your server.
If your service was exceptional, then you should leave more than 15%.
If you have never worked as a server or in customer service, then you probably don't understand how hard you have to work for your tips, and how rude, obnoxious and down right mean customers can be.
I hope this helps give everyone a better understanding of how it is for the restaurant staff and why tipping appropriately is important.