As Gabriel requested, here is a summary of the advice given by kendoinfo.com readers on the correct layout of a kendojo and the seating plan within. George did most of the hard work, but everybody contributed some really useful points.
Let’s start by clarifying the terminology. Kamiza means high seat, so does joseki. The difference normally attributed to the two terms in kendo is that kamiza is the side of the dojo where the teachers sit and Joseki is the end of the dojo where higher grades on both teacher and student sides sit. Shimoza is the student’s side opposite kamiza. Shimoseki is the end of the dojo where lower grades are placed. Whereas the kami in kamiza refers to “high” its meaning in kamidana refers to god or gods. A kamidana is literally a “God shelf” or a raised altar to the dojo’s Shinto gods.
As George pointed out it all depends on whether the dojo actually has a kamidana as to whether or not it should be laid out on traditional lines, but as dojo around the world normally emulate Japanese dojo we will work on the basis that it does.
So assuming that the kamidana is in the centre of kamiza, kamiza should be located at the north side of the hall facing south. Joseki will be to the east and shimoseki to the west. Ideally the door should be located at the shimoseki end of shimoza but space and architecture do not always allow for this.
The most common seating arrangement is in grade order; instructors on kamiza side, students on shimoza, both ranged from lowest at shimoseki to highest at joseki. George made another good point which I will elaborate on. Grade is not only evaluated by dan and length of time in grade, but age and length of membership of a particular dojo also have an impact on where you sit. On the instructor side, shogo also has a bearing on your place in the line. It is pretty much clear cut that hanshi sit at the top of the line, but working out whether a younger kyoshi should sit above an older renshi would take the judgement of Solomon and fall into what my teachers at referee seminars often refer to as “the grey zone”. The trump card in this situation is that the dojo master or Shihan is always the boss and what he or she says goes.