Hi,
Whether to go wiki or blog, hosted or non-hosted, depends on a number of things. What do you intend to use the website for? Do you want posting access tightly controlled or collaborative? Will it be a long-term resource or will it go away shortly after the camp?
If you don't yet have strong feelings about any of those questions, you might make use of the wiki over at barcamp.org, and migrate content as your needs become clearer. The advantages are that someone else owns and maintains it, and it's linked to other BarCamp efforts.
I've been part of the planning of CURATEcamp, a series of unconferences around digital curation practice, so have some experience here. We started out using Google Groups "pages" feature, which is now going away. We considered using Google Sites but never got around to vetting it properly. We're now using a non-hosted version of Drupal alongside a non-hosted MediaWiki instance. There's no reason we couldn't use a hosted blog + wiki solution.
We like having the ability to write blog posts and have community member subscribe to the feed, and we like the collaborative editing of wikis, and we also are planning a *series* of events intended to help build community so continuity between events (and thus durable content and URLs) are important for us.
This configuration, I admit, may be a bit heavy or expensive for our needs. Another variable to consider: do you have someone who is interested in messing with blogs and wikis? We do, and that's the only reason we've got custom wiki and blog instances up, otherwise some combination of posterous/tumblr and pbwiki would have sufficed.
Best of luck,
-Mike
