There is a better way, at least if your goal is to get a fresher mix of your favorite songs, new songs, and stuff you haven't heard in a while. And it's (relatively) simple: iTunes Smart Playlists.
The main foundation for my playlists are taken from this fantastic article by Andy Budd, iTunes Smart Playlists. I highly recommend the article; it's useful and easy to implement. The basic idea is to create several "feeder" Smart Playlists: favorites, new songs, songs not played often, and a mix of songs that haven't been played in a couple weeks. All of these are combined into one "Master" playlist. The only real difference is that I try to rate all my music - leaving audiobooks, podcasts, and videos unrated so they won't show up - and as such my "feeder" playlists have a rating condition. Usually "rating greater than three" or "rating equals x", while in Budd's system, only the favorites playlist is rated. Budd's system will work fine, however, for anyone who is not as anal as me when it comes to rating their tracks.
My ":Master Mix" playlist is limited to eight hours of music, the maximum amount of music I imagine I would need for a workday.
Budd also uses his master playlist to make several genre centered playlists. I also do this, but I set up the same feeder system for each genre, instead of having it feed from the master list(since mine is "only" eight hours).
I name my genre playlists after radio stations around Laurel, Maryland, where I grew up.
My radio playlists are:
- : Radio (Alternative 99.1 HFS)
- : Radio (Classic Rock 94.7)
- : Radio (Indie 102.7)
- : Radio (Oldies 100.3)
- : Radio (98 Rock)
- : Radio (Hot 99.5)
- : Radio (95.5 The People Station)
All of these playlists use two feeder playlists: "Genre Feed" and "Genre New". "Genre Feed" looks for songs in the genre that have not been played in four weeks, have a rating over three, and selects two hours at random. "Genre New" looks for songs in the "New Music" playlist that match the genre, and limits the selection to one hour of music(the rating, and other considerations are already handled by the "New Music" playlist).
The ": Radio" playlists combine these two feeder lists, limited to one hour of music, selected at random. Since the "feeder" is twice as big as the "new" playlist, you should get a 2-1 ratio of "old favorites" to "new music". This can be tinkered with to your liking, providing you have enough "new" music to fill up the "Genre New" playlist.
This kind of set-up is perfect for a limited storage device like the iPhone. 8GB is not nearly enough for a sizable music library, so instead, my iPhone syncs the above Radio playlists and my Mix playlists. After listening to some music while I'm out and about, I re-sync it, and the playlists get re-populated with fresh content.
Still, I love having access to my entire library, because sometimes you just want to listen to The Replacement's entire catalog or you need to hear one of the more obscure selections in your collection. For that, I still use my video iPod with 160GB of storage.

