You will have so much fun!!! Here are a few of our favorites (yes, more than 3 -- how can we pick just 3?)

from the last 7 years:
Character meal: if you have little princesses, Cinderella's Royal Table in the castle is awesome. It is also hard to get. If you can't/don't want to do that, then you should also think about which characters your kids enjoy. If they are Pooh fans, Crystal Palace is lovely -- have lunch there when you've spent the entire morning in the MK, it's a relaxing break. If they are Mickey fans, Chef Mickey's is a lot of fun. It is also not in a park, so if you are taking a "down" day, it can be a great thing to do!
Lunch: Pretty much all of the Epcot eateries are tasty for lunch so I won't even go there. If you are looking for some quick counter food elsewhere, Pecos Bills at the MK has good burgers, and we are HUGE fans of the 50s Prime Time Cafe for a lunch break at MGM (portions are very large, so share and then you can have s'more for dessert!), or if you want a longer break in the day, take the boat from MK to Whispering Canyons at the Wilderness Lodge (although recent posts have me wondering what happened to the place we enjoyed so much 3 years ago). If you are near the boardwalk, Beaches & Cream is awesome.
Dinner: California Grill gets rave reviews. We personally really enjoyed Le Cellier and Chefs de France in Epcot. Boma was also very good, unless your kids are picky and won't try stuff on the adult buffet (the kids buffet was pretty bland and dry) -- it was the first restaurant our kids wanted to go back to the following year. We entertained out of town relatives at Flying Fish, on the Boardwalk, and they all seemed to enjoy. We went to Artists Point at the Wilderness Lodge WITHOUT the kids one night and it was REALLY good.
Anyone can have a single bad experience, so I'm not saying these can't be good, but we did NOT have good experiences/enjoy the food at the following:
Norway Princess Breakfast (horrible character interaction, barely any food)
O'Hana
Cape May
Commissary at MGM
1900 Park Fare
Yorkshire County Fish Shop (fast food place in Epcot, made my daughter sick)
Pizzafari at AK
Again, many people like some or all of those, just my 2 cents.
Have a wonderful time!!