Should I have one centralized site, or lots of local sites?

Hmmm... How many cities are there in the United States? The World? And what about those folks on the north side of Philly who are convinced that they share precious little with the people on the east side? For that matter, the people in the city of Santa Cruz, CA, have different interests than those people who live up in the Santa Cruz mountains, even though the Post Office thinks they're all in the same town.

You can see the dilemma, I imagine. :-)

In general, I think that it's a smart strategy to try and identify unique interests and concerns of your target demographic, slicing into subgroups as makes sense, but I don't agree with the infinite subgroups approach that some sites take because there are serious problems that can arise.

First challenge: what if you split something into cities, but don't have any data for a specific city that someone seeks. Do you show them a blank page? Show them data for adjacent cities? Invite them to submit their own favorite venue? None of those are good solutions because they don't fulfill the promise of a local dataset for that community.

Second challenge: more local sites or areas requires more data collection and management. Instead of "cool ski sites in the US", having "cool ski sites in [any one of 78 different ski resort areas]" means that you need to have at least 4*78 entries, whereas the former could easily have a dozen entries and be starting to gain visibility and traffic.

Third challenge: relevance. Once you start slicing your site to meet the perceived needs of local audiences, where do you stop? Do you offer it by geographic region and age? Ability? Education or training?

You can see that my belief is that it's better to have a central site that spawns sub-sites or specific areas for audiences as the content is available, if at all, and that having one central umbrella means that it's considerably easier to manage the project and have relevant and valuable new information added with frequency, even with a small staff.

One final thought: pay attention to the main players and competitors in your given market space. If they're all doing local sites, ask yourself if they're doing a good job of it, or whether they're just doing an "SEO play" without adding anything to the content and value of their presence.

Hope that's helpful advice!