I would like to see that David Copperfield's Underground Restaurant open either in DHS or DTD like it was supposed to. I thought when first reading about it to be so amazing your chairs you're sitting on would levitate or disappearing plates of food.
How about a table service restaurant in Tower of Terror, you know, where the Sunset Room is. There, they can actually serve 1930s styled food while experiencing Twilight Zone mania, with references to those episodes.
Finally, I think a futuristic restaurant with a resemblance to Horizons would be a perfect fit in Electric Umbrella's location. After seeing pictures from a blog of the undersea restaurant's scenes, it would be cool to combine all those concepts as one. Of course, this one is really wishful thinking, but dreamers do dream, do they?...