Thank you for the suggestions, but they don't really work for me. Firstly, I don't rate any of my tracks. No-one has really made it easy enough to make it worth the time investment. If, when music was playing, you just hit 1-5 on the keyboard to rate a track, that would make things a lot quicker. Even better, would be to rate things on a better/worse system based on what was last played, which would eventually rate all your music automatically without you having to decide whether something was a 4 or a 5 etc.
But I am not looking to hide tracks. If I wanted that, I would just remove them from the library. I am wanting them to be visible, and to be able to be easily toggled on or off. It's just that there are some tracks that I don't ever want to come up randomly, only when they are specifically chosen.
The more time I spend with MC18, the more it feels like the interface was designed by engineers. It's very powerful, and very flexible in some ways (which are far more complex than most users need) but also lacking in "simple" features like this.