Don't know about LCD, but TFTs has 60 and 75Hz. I use 75Hz of course, always use the highest refresh rate for the given resolution. Also, a resolution very high will produce a low freq, so for 17" i would suggest 1280 at 75 much better than 1600 at 60.
For CRT monitors, the highest refresh rate for the resolution you are using is the best. You may have to use the little adjustment buttons on the front of the monitor to get the picture right on the screen, but the picture will be better and games can actually play better.
For LCD monitors, they are happy to run at 60Hz...The technology they use isn't really tied to its refresh rate.