Here is a screenshot of my layout plan for my N scale layout. The staging tracks to the right are underneath the layout and are accessed by 2% grades either side. I am planning on having lift-out sections for emergent train-wreck cleanup as well as viewing ports in the fascia so I can guide my hands up into there (from underneath) if I have to.

The doorway is on the bottom right and the layout room is accessed by either ducking under the layout or lifting out the narrower 12" section that spans the door. There is a switching lead for the mill which just fits behind the door when it is fully opened.

The triangular area in the upper left is a "staging pit" where the interchange tracks can be made up and the staging tracks below can be accessed if nescessary.

The grid is a 3" grid. The room is 10'X10'.

Hard to believe, but there are 51 switches in this plan. I just made a major purchase with Fast Tracks, so I have a lot of track construction ahead! I should have bought some shares.... maybe I should get some shares in Circuitron as all those Tortoise's are going to bankrupt me!