I use two options at opposite ends of the quality spectrum. On the 60gb iPod I keep Apple Lossless files because even with the large file sizes I can still keep more tunes on there than I can possibly listen to, even on a long trip. All my music is stored in Apple Lossless on a hard drive that's used as a server for my main system and it's convenient to just copy them over to the iPod.
On the 1gb shuffle I use 128kbps files and find that the quality is fine for that use. There's a nice feature in the iTunes settings for the shuffle that converts any bit-rate file to 128 as it loads it onto the shuffle.
When I had my first 10gb mp3 player, I almost always used 196kbps. At that bit rate the quality was more than good enough in most of the environments where I found myself using a portable player.
On the 1gb shuffle I use 128kbps files and find that the quality is fine for that use. There's a nice feature in the iTunes settings for the shuffle that converts any bit-rate file to 128 as it loads it onto the shuffle.
When I had my first 10gb mp3 player, I almost always used 196kbps. At that bit rate the quality was more than good enough in most of the environments where I found myself using a portable player.