For rectangular-shaped, orthogonally-aligned rooms, you can use a Bounding Box Min-Point and Max-Point to get the X and Y dimensions of a room.
The problems I would expect are irregular-shaped rooms and rotated rooms. Corridors tend to be either or both of these which can complicate things.
For specific locations like areas in front of lifts, you can place an element representing the minimum clearance and then generate a clash check to see if that clearance zone is free of obstruction.
EDIT: How to find the center path of a surface - #12 by Yna_Db
This looks to be a useful read on the topic.