I always love watching how your layouts evolve. They are great and have given me so many ideas.
By nature I am more more of a minimalist though I realize that the size of O scale often makes it difficult to have a lot of action, without dense track work. So I think it would be interesting to see what this plan would look like without the upper loop. It would free up space to move the mainline to the left a few inches and add some possibilities to the yard area. Maybe space for an engine service area - a couple tracks.
These are just thoughts I had.
Keep up the great work!