Walking that much, I ate just fine. I still don't get the too much food thing and I like food. I'm a picky foodie, but it is what it is at Disney.
You get a plate of what you like at a buffet, see some characters, and you've gotten your money's worth. There is no more to get out of it. Yes, someone else may like Pooh before getting stuck at Rabbit's out-eat you capacity wise, but is that a goal??? Yes, you're going to eat another meal again in 6 hours but inbetween you'll be walking ten or more miles and only sit down in rides for a few minutes.
Even at signatures, are the appetizers and desserts SO HUGE? Is it the best you've ever had so you have to go back for thirds because you might never eat something do delectable again?
We do 3 character meals a day (someday when kiddo is older we'll switch to signatures and I'll BEG her to nostalgically please do ONE character meal

) so upgrading during free for us dining makes tons of financial sense and park time sense. The only characters we intend to wait a while to see is A&E if I don't get a fastpass this time. (fingers crossed for me -- it's in a few days!)
Going deluxe when each meal is like $50/pp also makes sense. And having an allergy chef at meals when my daughter and I have serious food allergies for us makes sense.
At home, we really don't do fast food. We can't really risk it and as a result, I might have the only toddler in the world who doesn't understand the appeal of a chicken nugget and hates hamburgers even if she's starving. Even a hot dog she picks at and basically just licks the ketchup off. But give her an 'adult meal'? Steak, chicken, baked potato, steamed veggies, mushrooms, tomatoes, etc.... She's a happy girl. Throw in a cupcake and some characters and for about the same amount of time, the meal becomes an event full of magic (& IMVHO that certainly beats standing in line to see characters and having fast food).
I will also say, our better meals were made by the allergy chefs. It was a chef listening to what you can eat and what you like and then coming out with a fresh salad dressing, grilled chicken or steak, a plate of cherry tomatoes, a skewer of grilled mushrooms, etc but really just some of my kiddo's favorites.
Our worst meals were easily the counters we tried that were super highly recommended and we found truly horrible. You can only send sucky food back so many times before you realize they just don't have the ability to make it any better.
I think you have to know what your family eats and likes to do and then go from there. We did see a family with teens at several character meals (CP, Akershus, etc) and the kids were totally bored and simultaneously traumatized at their parents wearing mickey ears and cheering when the characters came over like they must have done when the kids were younger. I hope we have many more years before our kiddo is one of the teens rolling her eyes at us.
