Just a thought, RE: Rainbow Stairs.
I don't know if it's been bought up or not so far, but I have a theory regarding them. Wouldn't be surprised if they are going to be there for real. Going off what we know about the Marmalisation process so far what do we believe it's aim is? To make people happy and smile as far as I'm aware. We are also taking the Smiler and theming centrepiece to be the ne tools the MoJ uses to accomplish this, after their disasterous first attempts.
So how does this sound? You disembark the ride supposedly Marmalised, and you make your way up the Rainbow Stairs to exit the station. Once up these stairs you enter a corridor where they could either have a post show of some description, or just apt decor, with bright, vibrant, happy colours and some strange, out of place happy upbeat music (All the opposite of what we've seen and hears so far from the game).
The idea is that now you've been Marmalised this is how you feel, and what you see. There could even be a video of some form included explaining what you have been through. As a contrast if say the original videos in the main queue were all black, white, silvers, and yellow, this one could be all bright vibrant colours and have some effects added to it like daft rainbows and sparkles or something.
If you ask me it'd be a great way to bring the whole ride and experience to a neat close, and really top it off. For me a lot of themed experience rides all cut off very abruptly following their main show piece, and leave themselves very open ended. This would be a great way to combat that and draw the ride to a neat conclusion