I know it's not an ride as such, but is certainly a show / attraction;
I'd love it if Towers installed some permanent fountains on the main lake, install a decent PA system around the lawns / lake area.
They could program different shows to play thoughout the year, it will be fairly cost effective, given the water is already there, and would be a cheap way of adding a new 'show' on park. The programs could be changed throughout the year, perhaps a Scarefest themed one, or something to celebrate the new attraction of any given year.
Most staple parks around the world have some kind of outdoor water show bar Alton Towers, why have they not already embraced this technology?