The handymen will repair machines. One room of several can be 'turned off' by reducing the queue size to zero. This can be useful if you don't have enough money to buy a replacement machine and it has either a low strength or is badly damaged. Patients still occasionally manage to find their way to these rooms, but the room will be used only when the other rooms of the same type have full queues - in other words it acts as a spare. You will also hear a PA announcement that the room needs a doctor.
Patients hate standing, so build areas where they can sit and wait for a room to become available.
Plants make a room a better working environment for your staff, so make sure you 'plant' a plant in each. This is the first room that a patient is going to see. In here a doctor will talk to the patient for a while to see what symptoms they have. Based on this consult the patient will be dispatched to a diagnosis room for further analysis or, hopefully, onto a cure. The skill of the doctor in this room determines how complete a diagnosis can be made on the patient on each sitting.