Gold reflectors look best for B&W images, or when you need to bounce the light rays from the sun INTO shadowed areas that have a lot of cool, blue light. Indoors with flash or fluorescent or incandescent or quartz-halogen light, I would probably never use the gold, unless I needed a bit more specularity on human skin.
Silver? YES, for longer "throws". White? allllll the time, very often. Black side is for "subtractive light", and would be useful at times, in order to make light drop off in intensity more-rapidly. Again, for something like subtractive lighting a BIG black panel is going to work more effectively than a smaller panel will.
The thing is, to really get the most out of a subtractive panel, it needs to be quite large in relation, in comparison to, the subject OR it needs to be placed ridiculously close to the subject. I'd say think of a panel 3x the physical size of the subject if the panel is 4 to 5 feet away...
A good portion of these small, compact fabric reflectors are designed to make sales, and I think you'll find that working alone, the real benefits are going to come from using bigger, 42x42 or 42x60 or 42x72 panels that are actually big enough to make real, major differences in what needs to be done to the light, and they will allow you to do the job without the need to continually micro-manage a very small reflector that really does not have the sheer size to handle a shooting area that might be say 5x5 foot wide. I would say: make your OWN panels. No need for gold.
