Jerm, et al:
Over the years I have made many layout files, so many in fact, that I've forgotten what many of the do or are for. As a result, when I save a layout now, I place it in a Layout folder in my library with a screen shot of it as well as a quick readme file. In addition to the readme file, you can open the .lay file with wordpad and then you'll have a list of all the items in it for future use in a different installation.
While these shots show ships in them, I usually don't save the Layout file with ships or aeroplanes. That way the layouts are usable from theater to theater.