Bathroom design is as important, being the most frequently visited. Practicality and style go hand in hand.
Underpinning all of this is working out how these rooms will be used on a daily basis including knowing precisely what appliances (apart from those that are standard size of 60cmx60cm such as dishwashers) and fittings you wish to install before you start designing.
This will be key in determining the correct space around your appliances and fittings as well as the lighting, electric locations and pipe runs. These decisions will have an impact on the foundations drawings, i.e. exact locations for sinks etc. are important to know before they are laid so provisions can be made for them.
In bathrooms, consider early on if you will be going for wall hung sanitaryware as the pipes will have to be located so as to make room for the bracket that will hold up the basin or toilet.