This can apply to the setting, the type of group the suspects belong to, which mythological/horror creature the crime is briefly thought to be responsible for (like the recent Kamaitachi and vampire cases featuring Hattori), or which classic detective novel you'd like to see a Conan version of (Like the ABC Murders-inspired one from Volume 39 or the Hound of Baskervilles inspired one from Volume 70)
For settings, I'd like to see a case happen on: a suspension bridge, an airport terminal, and a water park, just some that come to mind right now.