This structure has been based upon a real, much larger building. All the elements are present. The building has a loading dock, entrance doors, and roof details. Next to it, a storage tank provides support to the main facility. In real life, this factory would be much larger, but the image of heavy industry still is conveyed in this smaller scene.
There are areas on the layout where you will want to have very dense trackage and structures. The center of a city, with its adjacent industrial areas, would have lots of buildings, lots of tracks. In addition, to accurately mirror the real world, don't move abruptly from dense city to a rural scene, complete with dairy cows grazing. In your research, you will notice appealing real and model railroad scenes. On the whole, you will find that these scenes do not crowd a large number of things into one place, and that there is a certain sense of correctness about the scene.
Although many of us will build a layout to occupy a fixed area, others will want to be able to expand theirs. If the latter is one of your goals, you can incorporate this into your design; what may be a short industrial siding in a corner of your initial layout could later be converted to a branch line leading to a newer segment of the layout. If you decide not to expand, this track still serves a real purpose.
By dividing the layout into zones, you offer the viewer opportunities to see the train actors in different scenes. Isolating the scenes from each other is necessary, and there are a variety of ways to do it. One of the newer developments is the use of the layout-dividing backdrop. Here, a piece of Masonite or similar material is set up across the layout. Holes are cut at the bottom of the backdrop to allow the trains to pass from one side to the other. The backdrop is painted a neutral shade of light blue, perhaps with some embellishment such as clouds, and the scenery is built up toward the backdrop. The layout has now been divided into two completely separate scenes. By doing this, you can have a dense city scene on one side and a rural scene on the other. The effect is startling!
There are also other, more subtle ways of dividing the layout into zones of interest. Using bridges or tunnels will make the train disappear, however briefly, allowing you to play with the viewer's perception. Such a brief disappearance gives the impression that the train has traveled much farther than the few inches it actually has gone. Even passing through a deep cut in a hillside on the layout makes the distance traveled seem much greater.
With all that in mind, let's talk track here. You have a good idea about what you want to happen, but you need to determine how much space it is going to take, or how much track you can get into the space you have. There are several ways to approach track design. One of the quickest ways is to go out and buy a load of track, piece it together, and figure it out as you go. There is something to be said for this method, but it is inefficient and can be costly. Also, the repeated assembly and disassembly of the track parts invites problems, particularly with the distortion of the delicate rail joiners. There are easier ways.