As with other rooms in the house, create different levels of lighting.
The main three are ambient - task - accent
Ambient
The ambient layer is the general lighting. It is the electrical equivalent of daylight. For most homes a central pendant provides the ambient lighting, but this alone can create a flatness that is not desirable. It is useful to achieve the ambient lighting from a variety of fittings such as wall lights, uplights, downlights and floor lights.
Accent
The accent layer adds drama to your room. It creates areas of light and shade, which in turn give your scheme texture and depth. Spotlights, downlights, uplights, picture lights, and track lighting can be a useful source for accent lighting. Use it to show off features in a room or to highlight items such as pictures, sculptures or plants.
Task
The task layer is the lighting you require at certain times to perform certain jobs such as shaving, make-up, contact lens. The purpose of task lighting is to provide the light you require, for the task you are performing when you are actually doing it. Spotlights are useful forms of task lighting.
Essentially, this means not relying on just one source of light. So, think about using an ambient wall light operated by one switch (and related circuit) and, for example, Accent/Task either over-mirror light or a pair of wall lights of an appropriate IP rating. Sometimes an over-mirror light produces an unflattering light so consider fitting a pair of lights either side of the mirror instead which casts a more even light.
Consider using Accent floor lights too. LED Pave fitting can be used in bathrooms, set into the walls.
I recently check a major DIY store and they had flush shower down lighters that would improve the beam width.
My choice would be to focus on task lighting areas with flush down lighter spots (Special Shower Spot for bath/shower) One in zone1 and and ambients zone two by the wash basin/mirror Accents in zone three where there are dark areas or a towell radiator.
