Crystal PAlace has excellent food and if you're looking for a character meal, IMHO, it's one of the best on property.
Tony's Town square is a very pretty restaurant and does decent enough food, although for straightforward pasta dishes it's a little pricey by off site standards (hey you're in a themepark so I guessit's expected)
Liberty Tree Tavern is another excellent choice.
If you haven't booked anything and want a sit down (full service) the Plaza restaurant (tucked away on Main St) does nice sandwiches and burgers etc is often overlooked and has availability at short notice
On the monorail there are some excellent choices.
Character meals at Chef Mickey's (contemp) 1900 park Fare (GF) and Ohana's (breakfast at Poly)
Grand Floridian Cafe, Kona Cafe (poly) and concourse steak house (contemp)are all excellent places to eat.
If you're going UPSCALE California Grill (contemp) Narcoossee's and Citrico's (both GF) are spectacular.
Really depends on what you're looking for.