Receptional_Andy - 8:03 pm on Oct 28, 2007 (gmt 0)

Option A sounds like the best to me, purely because it seems to reflect the information hierarchy better. Of course, you would need meaningful content at each 'subdirectory' index page for everything to work.

too deep for SEO

Too deep really means 'not linked to often enough' rather than how many slashes are in the URL.