As mountain construction has progressed, my view of Horseshoe Curve and the eastern approaches to the Gallitzin Tunnels from the control panel has been blocked. This isn't bad thing, in fact far from it. Having the trains disappear from view adds interest and not being able to see the entire layout at one time makes it seem bigger than it actually is. The one down side is if train decides to derail or stall in this section of the layout, I don't usually find out until said train gets rear-ended.
My decidedly low-tech solution was to buy a cheapie door mirror from Wal Mart and screw it toe the angled part of the wall over Horseshoe Curve. It's not a perfect solution as I can only see part of the track in question, But hey, some is better than none right?