Marketing in Multiple Cities - Main Domain w/subs or Separate?

[hominid]

I'm going to be building out 5 local directories (to start) to market businesses. Would it be better to have one master domain with cities as sub-domains (e.g. www.mydomain.com/first-city) or separate, keyword targeted domains that focus on one city? What are the ups and downs to either?

[ckilgs]

Without knowing too much about the overall site / business goals, I'd personally go the subdirectory route (subdomain would be city.domain.com not domain.com/city). The reason I say the subdirectory route is because I can see maintaining 5 separate domains (possibly more in the future) quite the headache and I feel you'll get more SEO value out of keeping everything under one umbrella. Just my opinion but I'd like to hear what others have to say.

Cheers.