We found that the regular dining plan is worth the money, having just actually paid for it for the first time a few weeks ago.
I would say the best place to eat breakfast is the Crystal Palace character breakfast buffet in the Magic Kingdom. You get to eat good food and get to rub elbows with Tigger, Eeyore, Piglet, and Pooh.
For lunch, we tend to do quick service places like Cosmic Ray's in the Magic Kingdom, Electric Umbrella at Epcot, Pizzafari in Animal Kingdom, or the Backlot Express in Hollywood Studios. If we do a sit-down meal, we've found that the Wilderness Lodge's Whispering Canyon Cafe has good food, and Epcot's Coral Reef Restaurant has some great food there.
For dinner, I definitely recommend 'Ohana at the Polynesian, as well as the Coral Reef Restaurant (already mentioned) in Epcot.