Clean, efficient, optimistic, but not "perfect" kind of feel. I definitely don't want the kind of tomorrow that Wall-E showed us nor do I want to enter a world that is completely automated. I guess I want to feel what people from the 50's-70's would think about the world today.
A gritty world would definitely be welcome as a part of an attraction, like others have said. Sort of like how Ghost Galaxy has this element that makes you feel just a little uneasy.