Many people say you can't really tell the difference between a 320kbps Constant Bit Rate (CBR) mp3 and a 16bit/44.1K WAV file.
From a hard disc storage point of view the 320kbps mp3 is smaller than a WAV but from a CD point of view the length of the song is same (and thus the used space on the CD is the same).
All things considered I burn 16bit/44.1K to a CD. Occasionally I will burn a 24bit/44.1 to CD.