Not a ride, however I'd like to see an UP dining experience.
I think it could be really easy to do, outside simply looks like the house with the balloons coming out of the top, inside is a restaurant in which the windows are screens so that it looks like you're flying through the sky. The floors could gently rock, and there could be creaking, etc... There could be an old record player in each section, banging out some vintage tunes. Would make for a really unique experience, and give UP a decent bit of presence in the parks.
I'm not sure what food I'd want served here, not given it much thought. Perhaps some sort of grandma/Nan style type of food.