Bedrooms are very private spaces and often reflect the individual/s who inhabit them so they need to be comfortable and flexible. Remember most people only use their bedrooms for sleeping.
When allocating space for the bedrooms try to keep the following things in mind;
In summer it is nice to have a cross breeze through your bedroom so plan for windows that are orientated to allow for predominant breeze patterns.
Will the bedroom double as something else during the day?
Make sure a bedroom size will suit your future needs.
Children require a desk for study, and this is best in their own environment, namely their bedroom.
Some children like to display their own craft-making abilities, making models, sculptures and painting means the floor covering is very important, a timber floor with a rug might be more serviceable than carpet.
For young children; remember they grow up quickly so don't get stuck with a room that is too small to do anything else with.
The master bedroom should be large enough to contain a king size bed, dressing table, chair, bedside tables and perhaps a chest of drawers.
Make sure the path from the bedrooms to the bathroom is easy to navigate at night without having to switch on lots of lights.
The master bedroom should contain either a walk-in dressing area with robes, or at least built-ins. These are cheaper to provide in a new home than new furniture.
In order to maintain privacy, try to avoid bedrooms that have common walls .
Don't forget where the sun rises and sets, a teenage bedroom shouldn't necessarily face east, save the sunrise for those who will appreciate it!
It is usually not so important to provide heating and cooling in the bedrooms unless you live in a more extreme environment, maintaining a constant temperature is more important, this can be done with careful planning and some ESD (Ecologically Sustainable Design) principles.