Arrangement of components on rack

A picture's worth a thousand words. Does that make it verbose?  
https://systems.audiogon.com/systems/8367

First I will explain the system layout.  I am fortunate that my electronics are in a separate room, just behind the front wall for my speakers.  I route the speaker cables through nicely finished port holes in the baseboards.  There are ABS tubes running through the wall so the speaker cables do not touch wood studs or plasterboard.  The amp is on an amp stand and is roughly between the speakers (with the wall separating the two rooms).  The amp stand is made of constrained layers and the feet are solid 6061 aluminum cones with tularium copper spikes.  My equipment is on an equipment rack alongside the amp stand and the rack is made of constrained layers and with solid 6061 aluminum legs, cone feet, and tularium copper spikes.  Each component is resting on rollerblocks for internal vibration control.  I have a dedicated 20 amp line for this system.  Power cords and interconnect cables are kept as separate as possible and where necessary are placed at 90 degree angles from one another (not running parallel). 

So, that's the system and now for the placement to address the OP question.  The power conditioner is on the bottom level of the rack, next up is the line stage preamp, next up is the phono stage, and on top is the turntable.  There is plenty of space for each component in order to be properly ventilated.  I measured the distance between all component connections for all interconnects and power cords and ordered the cables to meet my needs.  Everything has been very carefully thought out for ventilation, keeping large power supplies at a distance from source, and minimizing cable length.  I think it has turned out nicely but have to admit, during the process of over 2 years I made a few changes of equipment and of their locations, all for the better, and that necessitated a change of cable length for a couple of components.  That was a bit costly but it was the right thing to do.
I am quite pleased with the overall results.

Four things that I try to be mindful off in arranging components.

1. Turntable on top and away from transformers or any component that can contribute EMF or noise, such as power supplies or power conditioners, to very low level components such as cartridge.  
2.  Phono pre-amp as far away as possible from any transformers or noise inducing components.
3.  enough space in the rack for adequate heat dissipation.
4.  arrangements such that the interconnect cables are as short as possible.  

enjoy

@millercarbon Thanks for the great advice!

Wow-a! So many fascinating responses. And here I'd thought I'd asked a simple question. Never on Audiogon! Thanks so much to all.
-- Howard