Wow, this is an old thread.
I use CUE/FLAC for my original masters, because it allows me to recreate the original CDs if I need to, and also allows me to generate any other lossless or lossy format I want.
There's literally no reason to go past 44.1KHz/16 bit for playback. Higher sampling rates produce sound that's better than human hearing. There are a few people (I used to be this way when I was a teenager) that can hear over 20KHz, but there's nothing musical up there, because mixing engineers can't hear it. Everything above 20KHz is generally whiny, nasty noise that you'd want no part of. I used to hear analog TVs ring, I think probably at around 25KHz, strongly enough that I could tell if TVs were on inside a house from outside, through the walls. But it's just an unpleasant noise, it's not music. Nothing up there is music.
The only reason to use 24-bit depth is for mixing, so the quantization errors drop out when you downmix the final cut to 16 bits.
For actual day-to-day playback, VBR MP3 at ~192KBps has always been fine for me. Because space on portables has gotten so large, I've gone to ~256Kbit Vorbis in some cases, but at least with my ears, there's really no reason to. When I'm streaming Radio Paradise, I often use their 320K AAC stream, although again, that's way overkill. They even stream in FLAC, but I don't bother with that.