When I was a young-en I remember seeing tidal wave and thinking how ridiculously tall it was, and the occasional burst of flames making me jump. Sadly neither the gas or water effects will return for a reason which I think has been posted about a million times. I always thought a bit of low-lying mist in the cobra roll pit of Colossus would look nice, hiding the actual depth of it. I could give a ridiculous list of all the effects which would enhance each ride but I don't think I'll worry.