There is a formula like that of Bringhurst for the 66 characters to calculate the height of the cage of the text? or is it just a question of personal pleasure?
for examples i have found this two command in classicthesis.sty
\areaset[current]{336pt}{750pt} % ~ 336 * factor 2 + 33 head + 42 \the\footskip
\areaset{336pt}{761pt} % 686 (factor 2.2) + 33 head + 42 head \the\footskip 10pt
what means:
686 (factor 2.2) + 33 head + 42 head \the\footskip 10pt
and
~ 336 * factor 2 + 33 head + 42 \the\footskip
?

