I really like the general arrangement of your plan. The problem I see is, you have a number of long stub-end storage tracks that trains will have to back in or out of, using a curved lead inside a tunnel. If you want to keep those long stub-end tracks, you should at least have a wider radius approach track that is visible.
My own preference would be to have long double-ended tracks to park trains on, because it facilitates operation of different trains without a lot of switching. They could curve along the full length of the layout. To reduce the need for expensive wide-radius switches, you could have "serial staging" on a really long siding/alternate route.
Another preference for me is to have a choice of flat loops for running most trains, and an optional graded route. It can get tedious to constantly be adjusting the throttle for a long train on an up-and-over route.
Not everyone needs wide curves, and big articulateds don't look so great even on O72 curves, IMO. An advantage with the curves you used is that your tables and peninsulas can be narrower, so you don't have as many "long reach" issues. And you have a walk-in plan without duck-unders or drawbridges. Of course, your minimum radius standard depends on the kinds of trains you want to run.
