Rather than placing random amounts of gold on each tile in a special room that generates gold on each tile (zoo, leprechaun hall, and any other that might get added), bias it so that there is more gold in the corners and along the walls, on the basis that things tend to accumulate in the corners of rooms. Should work on irregularly shaped rooms as well as rectangular ones.

One possible algorithm is that corners get 3 “helpings” of gold placed on them, walls 2, and every other space 1.

Another take is to instead put more gold into the center of the room and less further out, possibly guaranteeing some dragons on top of the biggest piles.

Treasure zoos try to generate only “animal” monsters (those that have the M1_ANIMAL flag).