hi ian

i sort of have the same approach ... for everything but portrait work, but not really.
i usually have 2-3 views from an assortment of projects if i am trying to get architectural work.
but somewhere between 15-20 images, if it is more portrait.editorial work a variety of portraits
maybe of people they might know, or stories they might have heard of / read ... and a few tear sheets of the work in print.
if i am showing the portfolio "locally" there is 1 image that the paper i worked for sold for ad campaigns all over the place
it was on billboards, in print, on sides of buses &c and i make sure to end with that ...
people figured out where i shot it from and now everyone uses that view ... lol its kind of funny to be honest.

i also have a special portfolio which is of people at work and where they work, that i sometimes bring, like you do, work in progress ...
the images go in a leather bound book and the person and his/her workplace are each "spread".
all the images in that portfolio are printed the same aspect ratio/cropping whether they are 35mm, 6x6 5x7 &c to give it a continuity.

i used to have my website have more of the images, and the portfolio/s be a "taste" my site is being rebuilt this summer and i will probably do something similar
as i used to do ..