this is where plotmaker comes in . . .
draw as you want to in archiCAD - set the pens/thicknesses as you like to draw and see them on screen (establishing some kind of office convention for this would be handy so that people can move from project to project and not have to re-learn a pen set).
then,
in plotmaker, after you have imported the drawing, select it and go to Options->Drawing Pens & Colours. here you can amend the
output attributes of all of your pens. this won't affect how they appear in archiCAD - just plotmaker and plotmaker's output.
if you are using 8.1/3.1 be sure to select the drawing and in Edit->Drawing Settings change the 'attribute update rules' to ensure that archiCAD won't overwrite your plotmaker pens the next time the drawing is updated.
if you have established a pen set in archiCAD that you use for all of your drawings, i.e. the pens that you use for greyscale are the same pen numbers on all jobs, you can create a plotmaker template file that uses a uniform pen set throughout the whole layout book, overwriting the pen sets imported from archiCAD.
i have not done this myself, but i would think that it is a combination of editing the 'Book Pens & Colours' (Options->Book Pens & Colours with nothing selected in the layout window), and setting the 'Drawing Attributes' preferences (Plotmaker->Preferences then click through to 'Drawing Attributes') to "Uniform Pens & Colours for Drawings and Book". again i would think that you have to ensure that your 'attribute update rules' are set so that archiCAD doesn't overwrite them on future imports. having seen matthew lohden speak at this years archiCAD university, i think that he's probably the man to ask about this! matthew?
also - be sure to have 'greyscale' or 'colour' selected in the books output settings (Book->Book Settings), or they'll all come out true black anyway!
hth
~/archiben
b e n f r o s t
b f [a t ] p l a n b a r c h i t e c t u r e [d o t] n z
archicad | sketchup! | coffeecup