This is the stuff I live for. I plan my trips around dining. Having an 8 and 6 year old and living in Florida and being passholders, Disney World fills my dining bill for 4 vacations a year.
Best Seafood: Narcoossee's at the Grand Floridian Resort (Yes! Better than the Coral Reef for taste. Fried Calamari with Peppercorn Dressing, Seafood Chowder and Pan Seared Scallops)
Best Italian: L'Originale Alfredo di Roma at Epcot (Mozzarella alla Caprese and Spezzatino di Vitello)
Best Steaks: Le Cellier at Epcot (Cheddar Cheese Soup, Herb Crusted Prime Rib)
Best Spicy Food: Jiko at the Animal Kingdom Lodge (Duck and Pork Firecracker and Seared Jumbo Scallops)
Best Children's Food: Chef Mickey's at the Contemporary (It's a character buffet breakfast that offers a good range of different foods, but it is a very light and cheery atmosphere that just gets the day off right.)
Best Deserts: Bistro Di Paris at Epcot (Okay...they probably won't just serve deserts but...they change the menu quite often, but always have a chocolate sampler that will floor you.)
The only other place that just stands out on it's own for a wide selection of different types of foods is the California Grill at the top of the Contemporary.