Re: breakfast on the last day - of our 6 family cruises, we've eaten in the dining room exactly once. We did not enjoy it - it felt rushed (there was enough time, but the focus seemed to be on getting us in, fed, and out as fast as possible), and crowded (everyone's carryon luggage, tons of people everywhere). Every other time we've done Cabanas - usually there are not many people up there, we get an outdoor table, and enjoy one last time eating on the deck, at our own pace, then walk off when we're ready.
We also decided we don't like packing early to have luggage out for pickup, which means we carry it all off ourselves, and that wouldn't work in the MDR breakfast. We can have it with us at our outdoor table on the top deck easily, though.