I would recommend finding out which places are recommended, but a few in each park. We crossed the MK last trip to get to Cosmic Rays - I'm fine with Peco's Bills and I don't think its worth the walk (I was indulging my husband). Likewise, I wouldn't walk from the back end of Epcot to go eat at Seasons, there are several good counter service restaurants back in the World Showcase. The parks are large, and sometimes its best to "make do" rather than spending fifteen minutes getting to "better." (Which sometimes means a Mickey bar and better food later).
Animal Kingdom generally has good food (if you stay away from McDonalds), haven't had a bad meal or snack there yet. MGM is the opposite - although the food there is certainly edible.