Thanks for the ideas! We need 1 meal per park, ideally onsite because I want to minimise walking in the heat and travelling through crowds. Air conditionning would a plus since we are going in August. We went to WDW two years ago and were able to find lots of chicken nuggets/tenders in different places...hoping they are still on the menus because its the main thing my kids eat at the parks (sigh...). Do you know if Sci-fi diner is loud? I know my son would love watching movies and sitting in a car.
We love Sci-Fi, but it can feel loud - and some of the sound effects used in the old clips of movies and promos can have a sharp, sudden sound to them. Visually it's "noisy" as well - the screen dominates the dining area, and all of the cars face that screen. Obviously, the more people that are in that room, the better the acoustics become; when it's less than half full, it feels like the sound just bounces around in there.
The "cars" can seat 2 adults comfortably, our family usually sits 2 to a row. Because the car-tables face the screen, there's not much conversation - most folks watch the screen.
The content on the screen is a mix of old clips of inventions and former future technology, along with clips from old science fiction "B" grade movies from the late 40s/early 50s. Interspersed are the old concession stand "commercials" that used to air at real movie theaters and drive-ins back in the 40s/50s and 60s. Nothing really super "scary", but it's not everyone's cup of tea. My hubs doesn't see the humor or fun in it all... the rest of the family thinks that it's high camp, and the epitome of fun LOL. Your mileage may vary (pun intended).
If you can get one of the "umbrella" tables at the back of the room, it doesn't really mitigate the volume issue with the content being played on the screen, but it lets you see all of the "cars" (they aren't really cars, but they are awfully cute!) parked in rows, and it feels a bit less... hectic to me, even though you are sitting right next to the service counter where the wait staff is working. We often request a table back there, simply because we like it better; you don't have to face the screen straight on if you don't want to.
The last time we were there was in September 2018.
I can second Garden Grill at Epcot, especially at "off peak" times. Overall an excellent experience - because the dining room is constantly moving above The Land below, there is a point where you hear the dog barking almost incessantly. We block it out, but I can see where it might bother some folks.
At HS, I feel like you might be a bit limited right now as far as an overall quieter place for table service. The Hollywood Brown Derby, maybe? For a QS option, the ABC Commissary is indoors, with lovely AC, and although it's large, it's easy to find quieter, less hectic areas.