I'd love to see an R-rated 'Scooby Doo' movie.
I have felt this way since the 80's when the thought occurred to me...unlikely as it is to actually happen, it would be really neat to do an R-rated Scooby Doo movie, in which the monsters are actually murderous; and all the spooky sleuthing action would have an additional edge. In other words: Make it scary! Make it more serious! Such a thing could still be funny and goofy and flirty to a certain degree, and you could keep the cartoon colors and the groovy van and so on. But make it something surprising.
Again, it's unlikely this would ever happen. But if it did, I would be right there for it.