If you get a full identify insight (either exclusively from a throne, or from any source) but everything in your main inventory is already fully identified, all items you are carrying in containers recursively get fully identified as well.

Add a throne effect which either copies the confused noncursed effect of a scroll of taming, or mass-tames monsters in the current room. Either of these gives the player an incentive to sit on the throne without killing everything in the room first.

If you get crowned on an altar, it becomes a throne which will give you one guaranteed wish, and then has no effect other than to make you feel very comfortable there. Not specified what will happen if the altar is in a temple with a priest tending it.

One of the random throne effects is to tame monsters nearby. However, monsters that normally generate in throne rooms are immune to this effect.

Add a random throne effect that polymorphs you into a level-appropriate royal monster.

All thrones are considered historic and Archeologists get an alignment penalty for making one disappear.

Praying while standing on a throne, assuming you’re in good standing with your god, causes the god to have an increased chance of crowning you. Possibly, they always crown you if they decide to grant a boon and you are in good enough standing to be eligible for crowning.

Throne rooms should place the throne along one wall, preferably the narrower wall of the room.

Mimics can mimic other pieces of furniture like sinks, thrones, and altars. (They can already mimic doors and stairs.)

Monsters that hide under objects can also hide under or behind various types of terrain, such as sinks, ladders, thrones, and gravestones.

Thrones have an affiliation with a monster. Only the affiliated monster can sit on it and use it. It starts out as the king monster generated on the throne. If the monster dies, its killer becomes the new affiliated monster. This would need some flavor for why the king doesn’t just sit on it and use it until it vanishes; there are a few possible ways to handle that. One is that though the throne effects are good, the king is flavored as not wanting to lose the throne. Another is that throne rooms will start empty except for the king and maybe a couple guards, and the king does in fact use the throne’s powers against you (without risk of it vanishing since he is the original owner, or something).

If the player sits on a throne after being crowned, even in non-royal polyforms, they get the royalty message.

Thrones will not disappear in a puff of logic unless at least one interesting effect from sitting on them has happened.