What rollercoasters did you want to ride before they got torn down?
Personally I would of wanted to gone on the following coasters.
Black Hole (Alton Towers)
Corkscrew (Alton Towers)
Son of Beast (Kings Island)
Flashback (Six Flags Magic Mountain)
Knightmare (Camelot) - Park closed and this coaster will most likley get relocated, but will most likley have a different name.
Thunder Dolphin (Tokyo Dome City) - I know this coaster is SBNO and has been so for the last couple of seasons, but I sadly really doub't it will reopen, but I don't think it will ever get torn down because I think it would cost them allot of money to remove it.