Q: I think the new Genius Mix Playlists in iTunes 9 are great, but how can I prevent them from playing holiday tunes and Christmas carols in September?
A: The simplest way to deal with this is to UNcheck the tracks in iTunes that you do not want to play as part of a Genius Mix or Party Shuffle. iTunes will not play any tracks that are unchecked unless you specifically choose those tracks to play. This includes playback from within any type of playlist, from the normal library browser, or from within a Genius Mix.
Further, you can choose whether or not unchecked tracks are synced to your iPod or iPhone, and unchecked tracks are never synced to nor available on the Apple TV.
Note that you can check or uncheck all displayed tracks at once by simply holding down the CTRL key (Windows) or CMD key (Mac) while clicking on a checked or unchecked track; the setting will be modified for all displayed tracks. In combination with the library browser, this can be a handy way to check or uncheck all tracks from a given genre such as Christmas music; simply select the desired genre in the library browser, and then hold down the CTRL or CMD key while clicking on any checked song, and the selected song and all other displayed songs will be unchecked.
Note that this will only affect playback of these tracks in iTunes itself. If you want these unchecked tracks excluded from your Genius Mixes on your iPhone or iPod, you will need to ensure that the option to “Sync only checked songs and videos” is selected in your iPhone or iPod sync preferences in iTunes.
This will prevent any unchecked items from even being synced to your device, which will of course also exclude them from being played back as part of the Genius Mixes on your device.