Here's mine. This stuff is highly scientific. The custom module is at the left, where I would instinctively look for menu functions. The mix module is aligned with the mix functions of the track view. The playback module ties together the tracks pane and the clips pane. Tools, snap, loop and markers are right above the clips pane for minimal mousing distance. Event module is before screensets, to space things out a little. Performance module is the finishing touch of this masterpiece.
I wish there were spacers, I'd put one between custom and mix, one between playback and tools, one between marker and event, and a last one before performance, or something like that.
About the hypothetical spectrum meter module, my idea was that it would have a right click menu to choose any track or bus output. Context sensitive could also work I guess.