Not a terrible idea at all. I placed two mirrors across each other in our small bathroom. The mirrors are not of the same width but are the same design and at the same height to maintain simplicity. One narrow mirror above the basin, same width as the basin and tall enough so that our tallest family member at 2m can see their face. The WC also sits next to the basin but I did not want to extend the mirror from the basin. The wall space above the WC allowed for decorative items, eg artwork; narrow display shelf to add interest and texture. Directly opposite the basin and WC is a wide cabinet, and a large mirror to cover that width of cabinet and at the same height as the basin mirror. This mirror also reflects the artwork above the WC. It reflects so much more light and creates a wonderful feeling of space.

You can buy mirrored shaving cabinets of various widths and heights from many outlets, and even on ebay. The crucial thing is to ensure that the edge of a door isn't centered on the vanity basin otherwise your reflection will always have a "crack" down the middle of your face. You should also consider wall lighting as ceiling lights often put your face's reflection in shadow. In this photo the middle door of three is centred over the vanity basin to avoid the issue. Best of luck Dr Retro of Dr Retro House Calls

We too live in a cold winter climate with our bathrooms all on the southern side and faced similar issues as you do. One smaller bathroom does not have a window so we put in a Velux skylight which provides amazing natural light through the day. This may not be to your liking, especially if you have a period home. We also use heated towel rails and under tile heating (just enough to take the chill off and stop mould) in winter. Although we have a light in the shower recess, a bonus is the large fixed shower head with inbuilt LED, which at night gives the feeling of showering under moonlight. We chose light colours and mirrored recessed cabinets to reflect as much natural light as possible.

I just finished our new ensuite, which has a 1600mm vanity. I have 4 lighting circuits (switches): 1. 2 x downlights for the main bathroom in a similar place to you. 2. Another 2 x downlights ( 1 over each sink) 250mm off the wall (vanity is 500mm deep so halfway between person and mirror). 3. Extractor Fan / Heat Lamp and 4. Strip light under vanity for late night trips. The downlights are dimmable so you can have the main bathroom in a medium light and then you can choose how much to crank your vanity lights. The idea is that the light should shine onto your face hence they are installed in front of the person and they are on a gimble so they can be tilted to point at your face. I think you are in Australia so I can tell you they are the Domus Aqua Tilt 13 and are fully sealed (ip65) so no issue having over your shower, etc. They are also very bright as the light bounces off the white tiles, so really they are only needed when applying makeup. It's hard to know exactly where your lighting needs to go when you just have plans in front of you, but you could always get your electrician to wire both for wall sconces and downlights and then when you are further along you can choose whether to cut downlights or have wall lights. (Remember to take pictures and measurements of the wire locations before they close in the walls / ceiling!) If you try downlights first, it's also a lot easier to change your mind (i.e patch a ceiling) than wall lights as that usually means drilling through tiles..