I haven't stayed in a Concierge room yet but I have friends who have. I think all turret rooms should be concierge rooms.
You are allowed to check in and check out at the Marceline Salon on the 3rd floor. During the day (7AM-10PM), there will be candy, juice, coffee and tea. After 5PM, there will be soft drinks, cocktails and better snacks. There is also continental breakfast in the lounge starting at 7AM but your accommodation plan may instead include breakfast at one of the restaurants (usually Dreamers Lounge).
From the photos I've seen, unlike at the Sheraton or Hilton, the snacks during cocktail time at the Disney hotels would not be enough to substitute for dinner.