From all the data I've gathered, I see the best way to go is subfolder. An exception might be if somebody searches for weddings in Barcelona, I think weddingsbarcelona.com would come first, all other factors being equal. How much that means to you I'm not sure, but if you want a safe way to go I say subfolders, as your SEO efforts for one will also help the other.

Since your using Volusion, you'll need to check their documentation and contact their support to see what can be done. You can certainly add parameters and tell GWT how to handle these search and sort URLs, and you can edit your robots.txt to block search engines from indexing those overly dynamic pages.

Maybe you can turn off the sorting, pagination, and search features if you don't need them, but do it to improve the visitor experience, not for the search engines.

But I doubt those pages get indexed by Google now anyway, so don't worry too much. These aren't going to hurt your rank for the majority of your key words and target pages (unless of course your key word is "searching").

Coinidentally, I just touched on that today here http://moz.com/community/q/duplicate-title-tags-how-to-solve-that

I would go the way of subfolder over subdomain. There is a lot of info out there, but the crux of it comes down to all traffic improving domain rank for a single TLD. If you go the route of ccTLDs instead of subfolders, then you're spitting that rank among those domains. What circumstances would prevent you from concentrate all link juice to one domain? Then that duplicate content issue you're fearing becomes a nonissue.