I would look at extending the 45deg segment in the upper center of the drawing to just past the corner of the utility room enclosure. It would hold at least 6 yard tracks.
It is hard to tell the dimensions of all the spaces. Make the aisleways as wide as possible. I specified mine for 30" minimum but compromised and have some spots with just 28". After four years of operation I wish the layout could have worked with a 32" minimum. Another consideration is longer term changes. I find myself doing a lot more operation sitting on one of my high back swivel barstools placed in the aisles rather than standing like I used to. The layout has three exposed levels of track, 42", 48" and 54". Sitting on the barstool my eyes are about 4" above the top of the trains on the upper level, just perfect to see across the center peninsula. I am 5'-11". The highest building is 70" and the highest scenery is 72". The backdrop is 84" high. It gives a feeling of immersion into the display when in the train room. If you are only doing one level of track my recommendation would be 48" since you were not satisfied with the appearance of the 42" layout.
