Looks like you're looking for a small, hard-drive based player that will hold more than 20 GB of music. You'll need something bigger than that because you need to figure in at least 2GB for the operating system on a hard drive based player. So safe to say you should go for 30 GB or larger.
I don't think you'll find a player of that size that doesn't do video.
You've eliminated the most popular ones due to size/battery/format issues. Because of these issues, you've probably eliminated everything else too.
But here are some other players to consider may but they may not meet your size or battery standards:
Cowan iAudio XL5
If your're willing to sacrifice a lot of capacity, you could go for a flash-based player:
Sandisk Sansa e280
Has over a 20 hour battery life, according to cnet reviews. You can also expand the memory by adding upto a 2GB micro sd card. The operating system on this unit may only be about 200 mb or so.
I don't own any of these players, so I don't have any first hand experience with them. I own several iPods, including 5.5 gen video and 2nd gen Nano. I carry the Nano in my front pocket and it goes with me everywhere. The video iPod either stays at home or in my purse/backpack.
I'm looking for a compact player (ipod or smaller) that
-can store all 20+ gigs of my music....
-doesn't require converting files (sorry ipod...most of my music is stored as WMAs...)
-has a long battery life (sorry toshiba....too short).
-smaller is better (sorry creative, too big for my pocket).
Unfortunately, most of the best selling MP3 players tend to focus on video which is totally totally unimportant to me right now. I want small, long life, and universal....for music and music only.