A week ago I bought myself a Nike Psa[play portable mp3/wma player (rio based tech). After throwing in a couple of my old mp3s I started wondering about what codec/setting I should use. I will not be using these files for anything but my Psa[play (I encode the same files for quality). Mind that I will be using it with fair quality headphones and usually on my way to the university/work or sporting. There will be wind and cars, in other words not optimal surroundings for the audiophile. I hope you see where I'm getting at: I want the best sounding files (mp3 or wma - yes it's M$, but set it aside for now)with the smallest possible size. The player plays VBR BTW.
So, try wma @ 64 and 96, and mp3pro if your player supports it (and if you have mp3pro codec ;-) ).
Also try lame --alt-preset 80....100.
And choose whatever sounds better to you.
Lame --alt-preset 128 should sound even better (this will be ABR-VBR mode). If you are not too picky of high freqs, you may try this line instead:
lame --abr 128 -h --nspsytune --athtype 2 --lowpass 16 --ns-bass -8
Go for any higher lame bit-rate only if you find lower rates really REALLY very VERY annoying.
(But, as you said, superdigg, this is only for your player. not for archiving or sharing)
If you have plenty of storage, then you naturally can go for --alt-preset standard (higher if you prefer so).
kdo already mentioned some low end suggestions. If the bitrate is not a problem I think I would ABR to 160kbps or you could also test --alt-preset standard -Y (discards most above 16khz content).