Hmmm... Well... I haven't done too much that is long-term. Something like long-term slavery a week, a month, a year. That might be interesting. Of course all the details would have to be worked out, and it might not even be practical, but its fun to think about.

And something like long-term puppy play might be fun. Like drop into some kind of puppy mode and stay there.

And a group slavery thing might be fun. A few Dommes, and many slaves, several of whom are female.

I once read a short story about a guy who was somewhat subbie to his wife. One day the doorbell rings, he answers it. Its two female cops with a warrant for his arrest. His crime - not being a respectful and properly trained slave to his wife.

He was arrested, taken to "jail", stripped naked, deloused and then hosed down. Instead of being given an orange jumpsuit, he was forced to wear orange collar, wrist cuffs, ankle cuffs, and an orange chastity cage. His prisoner ID number was spray painted on his chest and ass, with a dangly little dogtag with his ID number clipped to his caged penis.

He's allowed one visitor, his wife. She's been in on it the whole time. She wants him trained to be a better slave, doesn't know how to do that, so she hired this "team of experts".

He's put on trial - naked of course - but he's gagged, unable to speak. The prosecution presents the case with the wife as the star witness. His defense attorney pleads guilty for him and throws him to the mercy of the court.

He's sentenced to six months prison of remedial slave training. The bailiff carts him off back to his cell, where his six months of prison / remedial slave training begins.

So... yeah... put that one on my list too.