Scenery for rides are already cool but it would be awesome if when you get on a coaster and start leaving the entrance, you can put a door that opens to the riders on the coaster so it looks like they are legitimately in a building, it would also be cool if later on the devs make it so if a coaster goes in a cave, it gets really dark so you would have to put torches around to light it up. Another thing they ar probably adding is more props that move.