There are several scenarios where an event or clue card directs that a monster be placed in a certain room. If the target room has multiple spaces, in which space should the monster be placed? I assume that these placements are the keeper’s choice, and that the keeper is free to make the placement to his own advantage. This can make a big difference. It could mean up to two extra steps for either the monster or the player. For a specific example, the Inner Sanctum scenario has more than one such event.

Any space in the room you want.

I've been playing that you can place it in any space within the room. I usually try to place it where it makes the most sense in context. If it looks like the monster is supposed to be coming from or heading to another room I'll place him accordingly. But really I think it's up to you as long as Monster X is in Room Y.

The rules are quite clear on this.
The keeper may choose to place the spawned monster in ANY of the spaces of a room!