The Blue Bayou is very popular. It's a bit pricey and I hear the food and servie is hit and miss. You're paying for "the view" cause its inside the bayou part of the Pirates ride. For nearly the same food but at a lesser price is Cafe Orleans. Carnation Cafe is taking reservations after the 14th of June, a popular place for a non-character sit down breakfast. My kids and I really like Big Thunder BBQ - all you can eat chicken and ribs with coleslaw and baked beans. Dessert is extra, but worth it IMO, the chocolate chip cookie bake with vanilla ice cream and hot fudge is fantastic.
If you make it out of the parks for an adult beverage I highly recomend Trader Sams near the DL hotel. we like Storytellers inside GCH. Haven't done thier buffet, but the menu food was great.
For counter service we have our must eats : Pacifi Warf Cafe in DCA, Golden Horseshoe with the Hillbillies, for burgers we like Hungry Bear. There is a new place in DCA that does great pasta and pizza but I can't remember the name, its in the back of the park in the boardwalk section.