Well I promised I would share some ideas for improvement, so here they are:
(explanations are below the images)
What I did with the bottom tracks is move the turnouts closer to the corners. Three benefits of this arrangement: (1) The turnouts are closer to where you can easily reach them from the end aisles; (2) the 2 bottom staging tracks are longer; and (3) the 'S' curves are eliminated.
[The curves might look a bit sloppy because I didn't do this with XtrkCAD, I just used a pixel-based image editor.]
The magenta-colored section of the backdrop is where you might put a pseudo "retaining wall" or fence of ~4 inches (10 cm) in height, rather than a solid sky. This will allow you to snap photos of the foreground at trackside-level with the staging tracks hidden, yet enable you to see [and reach] the trains if you stand up and look downward. I did that on my current layout, here are some pix:
View at trackside level
"Helicopter" view with staging tracks visible.
[A foot stool might be useful here, depending on how tall you are...]
On the left edge, I swapped your original #6 left-hand turnout with a #6
right-hand version to eliminate another 'S' curve.
There are several other improvements I could suggest, but I had to stop at this point because I feel like I'm fighting the flu and need some rest. I'm sure the others will share their ideas as well. Hope this helps...