I agree with chitown that Tidal Wave would be nice to have back, but of course we know that won't happen. :( I was really sad when it went away. I like what sits on that land now, but nothing can really replace it. An invertigo will be cool, although the lines will be long, just like they are at King's Island.
Guess on a second coaster? I'll go with WildOne on that and say mouse.