My planning process for the layout is based one over-riding principle: In order to preserve and create a running environment that is as flaw-free as possible, all scenery and landscaping will be done without the track on the table!
This, to me, is the greatest benefit of Kato's Unitrack. Since it is already ballasted, a lot of the traditional books and processes for landscaping (apply roadbed, apply track, scenery, ballast, clean up) are just not as relevant wiht Unitrack, so is there a better way? I think so.
However, this will mean some loss of detail. As good as the Unitrack is, its not perfectly realistic. I am willing to make that trade off, and I hope that the overall performance of the layout and cleanliness of the track outweigh any tradeoffs in the appearance.
So, after having decided on a final track plan (see below), and then adding in all the 'structural' elements (styrofoam, risers for grades) and the 'terrain smoothing' application with Sculpt-a-mold, I have a very ugly, but very useful layout wherein I layout all my Unitrack and do final checks for clearances and track placement.
I carefully mark the 'clearance' and footprint areas for the track, and then remove it all. Now on to the mess that is known as applying scenery (without the expensive, sensitive, and critical pieces of the track sitting in the line of fire to get ruined or compromised!).
The one thing that my process may not address (and I am admittedly a bit lazy to figure out how to solve for this) is that I don't disconnect all of the track, but keep it in 4 to 5 foot sections for easy replacement once the scenery is in place. This leads to the inevitable 'bowing' of the track as you attempt to manipulate 7 or sections in between the layout and a holding area while doing the scenery. I am concerned that this will loosen the uni-joiners leading to poor contact later. I may have to replace some of the uni-joiners as a result. We shall see.