iTunes is a fantastic music player. I have a huge music collection in my player, and all songs have received a rating. The smart playlists for iTunes are tha bomb, as you can virtually "program" how iTunes behaves and selects songs.
The smart playlist I am currently using for playing songs is the following:
The smart playlist only gives me 4 and 5 star rated songs, that I haven't heard for some time. Of these songs, only the 10 songs that have been played least are showing up in the resulting list. I'm playing the resulting playlist in a random order.
I've called this playlist "For sure: good stuff" and I stopped using any other playlists as this one guarantees good music.