New Layout - For your consideration

It's a cool design. I like the double track three times around with the elevation changes. Nice layout for train running and there is still some yard space. What are the dimensions and curves? Is 5" clearance enough?

The room is roughly 23' x 12'. The minimum curve is 0-80. I will not be running any contemporary rolling stock, IE containers or auto carriers. I am modeling steam era only, so the 5" clearance would be adequate for my use. (At least that is my thought). I am trying to keep the grades to a minimum at the 2.5% so that operations are not clunky when running the loop. 

How will you gain access to the center - duck under; lift out; motorized liftgate; swing bridge ?

Given those dimensions, how are you going to reach the far side  of the roundhouse area in that corner?  As a center of activity, it might be better to locate it towards the interior so it's more accessible, and also visible from more angles.

Trying to decipher the first image...is that a staircase up into the room in gray? So the layout is around the room, walls on all 4 sides?

I would agree that the TT should be placed in a more prominent area.

I wonder about how you're going to get access to that long stretch of double track that's in the tunnel? For a derailment or cleaning or whatever?  Perhaps crawling underneath, but do you want to keep doing that?  For a long tunnel like that I tend to want at least part of the top to lift off, but you have a lot going on over the tunnel. Perhaps something could be pushed around so the tunnel doesn't go under so much other stuff?

what are the layout dimensions?  just curious.  I like the layered approach.

First of all, very nice renderings.

I like how you used the entire size of the room to create long, shallow gradients.  I also like how you essentially created the longest possible loop that you could by going around the room three times.

As others have said, I would consider making the turntable more accessible, even if it meant creating some at grade crossings.

I would pay special attention to the two areas of the layout that are not quite rectangular.  The extra room beyond the turntable would be a possible place for a dead end siding to an industry or something.  Also, there is one random corner that juts out unusually close to your track.  I would seek to camouflage that with scenery or a tunnel or something.

To everyone, thank you for your input and thoughts. I have made some revisions to the layout. Added a new cutout to better reach the turntable (no issue with going under the layout). The cut out will also give me access to the track in the tunnel. Reorganized the siding and located the station on a dedicated siding track. Again thank you for the input.