We enjoyed lunch most every day in the sit-down restaurant. It was a nice break in the middle of the day to eat a relaxing noon meal away from crowds in peace and quiet.
Our thought is, even on days we have excursions, we like going back to the boat to eat because we know the food won't make us ill and better yet, it's paid for!!
We always did the breakfast buffet at Topsiders (very, very good!), so we skipped it for lunch.
However, once we did eat on deck outside, and the chicken fingers were surprisingly good. Sometimes just for a snack while swimming, we'd grab a piece of pizza or a bratwurst on deck.
And, although we've never done room service, you can do that at odd times when food service is not available.
That's the nice thing about Disney cruises -- you can usually always find most any kind of food you want if you know where to look.