Out of curiosity, how big's your Bryce scene file on hdd? And do you hear your HDD grinding away constantly while its rendering?

I once had to render something that was 36"x20" @ 300dpi and I ended up rendering it in quarters and then putting them together in photoshop - it didn't make it go any faster, just broke it up into bite size chunks.

Rayraz has made a pretty decent list, Also, I'd look at eliminating any soft shadow settings - they can eat render time up as well (basicaly simplify your light setup if you can).

Dreams are just nightmares on prozac...
Digital WasteLanD