There's a limited amount of keys and locks so if you add enough regions then you'll see "key #33" or something like that.
Here are some things I added:
for each unlocked dead end, there's a chance of adding a random lock and bonus
when placing a room, there's a chance of adding a secret room
when placing a room, there's a chance of a name and or some item
I'm not sure what theme or items I want in the final game, the ones here are just examples. Once I get the mechanics figured out (like how to create an interesting map) then I can figure out what theme I want to have.
I think I've crammed all I can into the map for now; time to start on actual gameplay.