qoms,
Three choices that I can think of right off the top of my head - floating light like the Glowbuoy, an over-the-rail light like the one I have called a Nitelighter, and one that installs in the return called the Aqualuminator.
My .02...
I've heard good things about the Glowbuoy, but from what I understand, you have to recharge it manually, which is a drawback for me. Hey, what can I say, I'm basically lazy..
The aqualuminator has to be installed in the return, so if I tried that, I'd have to do it during the winter, while the pool's lowered to the top return. Plus, I'd have to hook my fountain up to the lower return in the summertime...nah. Don't wanna do it.
So, that left option #3 for me. I originally bought a Nitelighter that was white light only, and had colored lenses to put over it for different colors. It lit up the pool fairly good, too. Had a 3 hour timer, so just turn it on and walk off. First of this season, I found that they make a color-changing Nitelighter, so I had to try it. The results were less than spectacular. Some of the colors really light the pool up (blue and green especially). The other colors didn't really do much. Here's a
thread that has pictures of my pool at night using the new Nitelighter. Here's another
thread where another member also installed the same light, with pretty much the same results. So, the white-only light did very well, but the color-changing one? Ehhh..leave it on green or blue, and it works fairly well too.
Hope this helps!
Mike