For most choral work, it's pretty unusual to need more than two layers in a single staff. If you have something like hymnal staves, JW Staff Polyphony is a Godsend (no pun intended.)
In treble staff, I would assign sopranos to layer one, altos to layer two, and then, in the bass staff, tenors to layer one, and basses to layer two.
I find it easiest to break the chorus into 4 staves, to best separate them for learning tracks for the singers. In fact, at this very moment, I'm working on a chart with 4 staves, broken out to 8, for S1, S2, A1, A2, and so forth.