I do this a lot, I've never really used playlists for music so just tend to pick songs manually and then listen to them for hours, days, or somethimes even weeks on end.
Here's some examples of tracks which have been left in Winamp / HiFi for a week or more:
Sarah Mclachlan - Sweet Surrender
Orbital - Halycon & On & On
Oasis - Slide Away
Leona Lewis - Bleeding Love
The Cult - She Sells Sanctuary
Stereophonics - Just Looking
Goo Goo Dolls - Iris
Foo Fighters - Everlong (acoustic)
Hurricane #1 - Step into my World
Joan Osbourne - One of Us
Jamelia - Superstar
Paul van Dyk - For an Angel
System F - Devotion
If I was list tracks I could listen to all day, it would probably rank in the hundreds. I tend to binge on single tracks for a few days and then leave them alone for months or even years.