I only have a 10 gig, and some if it is taken up by my wife's country music, which I never listen to unless she's in the car. Still, I've created about 3 different "modes" of using my Empeg that keep me from listening to some stuff for weeks at a time:

-Random "Jeff Radio" playlists: randomly play songs, picking one from each artist in a specific genre. This is the way I use the unit when I can't think of a better way. Also, because I have these lists separated by genre, I go weeks without hearing some songs.

-Random Albums: play entire albums at random, minus greatest hits. This captures some of the synergy in some albums and lets me re-discover stuff I got sick of and took out of my "Jeff Radio" playlists. Very often I bookmark this list and return to it later. An alternative to this is my "Desert Island" playlist that serves largely the same purpose, but is only my very favorite albums.

-All Rush, In Order: Contrary to my initial feelings with the Empeg, I have yet to get tired of listening Rush. I actually spend a scary amount of time starting from the first album and playing through to the last.

Alternating between these different modes keeps the music fresh for me, even with only 10 gigs worth of music. And I do use it at work all day. Of course, I've only had the unit for about 9 months . . .