Thanks for those ideas!
It seems like PHP code and switch statements will be my friends. I'm not an object-oriented genius like some of you out there, but I can easily handle this much coding.

It's a bit more manual than the other system I use, but will work perfectly well, and I think this will cover most of what I need.
To give you an idea of how the other system works, it's possible to set up, for example, and drop-down on a page which has a selection of colors, or a selection of banner images from a folder, either of which would be plugged into the CSS, and that sort of thing. I'm thinking that this would be a large project to make something like this, though. But maybe it will stimulate the imagination of some of our better coders here.

Thanks again!