Ki points should be per-encounter.
But I really really want to kill the "adventuring day" dead. I think a lot of players would have significantly more fun if it wasn't the core of DND.
Hear me out:
Double the number of Ki points. Double the cost of Stunning Strike.
Or: Monks have 3 stances: aggressive, defensive, and mobile. Switching stances costs a bonus action, and you can assume one stance freely when you roll initiative.
In aggressive stance Flurry of Blows is free.
In defensive stance Patient Defense is free.
In mobile stance Step of the Wind is free.
This way monks are not just a worse rogue, their basic abilities are now actual basic abilities.
That's very cool but DND will never have that kind of tactical depth without tying it to per-rest.
The adventuring day is garbage and it strangles cool ideas like this.
It could be tied to per-rest. Similar to the fighters' weapon mastery in OneDnD, switching stances could be tied to a long or short rest instead. Just call it something else, like katas. (Yeah, yeah, they are trying to move the monk away from the strictly Eastern roots, but they could give this as a flavor option.) You drill one of the katas in the morning and then you can use the basic ability associated with it for free:
- Kata of the Wildfire: aggressive stance,
- Kata of the Mountain: defensive stance,
- Kata of the Zephyr: mobile stance.
Yeah, but that's way less fun than the original. The original invites making tactical decisions every round.
Not-thought-through 1 Minute Solution #2: Using the one higher die for Martial Arts from the class table (always d6 instead of d4, d8 instead of d6 etc.)