Point well made and taken. That's why it's been somewhat of a struggle for me. I like the organization point that you bring up for sure, but I also like the traffic I pull in on some of the subdomains.
For example, I have a
Female Celebrities Site (FreshDames) but until recently, my subdomain for
Lindasy Lohan Pictures was actually drawing in more traffic that the main domain and all other subdomains combined; it is still ranks #2, drawing about 1300 visitors a day.
However, as I've begun building more pages, I've put them in separate directories under the main domain. They rank better as far as
PR, but they don't have the same traffic draw.
It's still a learning process for me ... time will tell.