Create a pool of unique “miniboss” monsters who do not randomly generate, but are eligible to spawn on the throne in throne rooms of sufficiently high level difficulty. The throne room audience could possibly also consist of monsters themed to whichever of the uniques generates in it.

Add “royal blue” as one of the randomized potion descriptions, for two reasons: 1) so that the monarch of a throne room can be given a royal blue potion as a pun, 2) so that there can be a potion that uses the “blue” color, which currently none do.

After killing certain type(s) of monsters (such as the monarch of a throne room), a timer may start that spawns an avenging posse of related monsters nearby.

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

Throne rooms generate their monsters awake, but also generate all their doorways as locked.

Pressure plate traps that cause all the doors of the current room to close and lock (doorways without doors could turn into iron bars or, on deep enough levels, all doors could turn into iron bars). Triggering this automatically removes the trap. Generated very rarely, and has special generation that occasionally makes it appear just inside a door to a throne room.

Statues generate in throne rooms, because they are the sort of thing a throne room would have.