Ventilation, heating and lighting are vital to get right if you want a bathroom that’s comfortable to be in. That’s because poor or underpowered lighting will make the experience miserable, as will a cold or stuffy bathroom.
Accommodating wiring isn’t usually as inconvenient as accommodating pipework but, again, having a precise location of where everything is to go is essential as it will have a knock on effect on first fix.
Think of everything from electric showers, to mirrors with bluethooth speakers. Also bear in mind a lot of furniture now comes with integrated lighting.
Some things can be retrofitted, such as speakers into ceiling LED light fittings, but if you want to avoid a patch job or being told you can’t fit the backlit mirror you wanted, plan early.