Often I have various design options for a site, but I want to evaluate them with the same set of scenes, which may change from day to day, or I might add background photos.
My technique is similar to what is described above, but I don't explode my component.
My file with the scenes is called something like "Project master file.skp"
There are a few top level components.
The Building design component is what I have 4-5 versions of, and I swap out which one I want to view or work on. When I make change to it, I save the component back out before swapping out for another one. I don't rely on it being saved in the master file. This was particularly useful when I had a project with tons of high res photo match scenes. I had to send my design back and forth via email, and this way I only had to send the model element, and not the larger file with the images. In this case my photo match was for the site context, not for the building design.
National Renewable Energy Laboratory