Magellen's is by far the ritziest restaurant on the property, though you can easily spend more on dinner at the high end restaurants in Miracosta and Ambassador. The prices are insane. I took a look at the menu for the high-end joint at the Ambassador last week when I was there and it was $130 a person for the fixed-price "set."
The Blue-Bayou in Tokyo Disneyland is the most "Disney" and atmospheric of any restaurant on property, it's not insanely expensive, and the food is good.
BUT, the best restaurant I've eaten at inthe Resort is Imahan in Ikspiari. It's a small branch of a famous restaurant from Tokyo and they specialize in Shabu-Shabu and Sukiyaki. It's amazingly good and will run you about $70 a person (about average for this type of restaurant in Tokyo). It's located in "Chef's Row" on the fourth floor.