I am utilizing a wildcard subdomain to handle the majority of my demands but I am encountering an problem of having among my subdomains (let us say, wiki.domain.com) to load first.

I realize that loading this in a httpd.conf or something like that would certainly be considered a situation of turning which VirtualHosts load first, however i am using a2ensite and sites-open to manage my domain names (individual files for every domain), which, to my understanding, means I've no real method of identifying which domain names are "loaded" first.

I'm running Ubuntu Sturdy.

In my opinion an order of loading comes from the title from the configuration file within the /etc/apahce2/sites-enabled directory. if you wanted one loaded first, you'd title the file 000-wiki.domain.com (or a2ensite 000-wiki.domain.com)

From curiosity, how come an order matter for you personally?

(As this question relates to system administration, it's more appropriate for serverfault.com.)

Under Debian and Ubuntu's default configuration, sites are loaded from a to z (using Apache's Include directive), so that you can alter the order by which your sites load by altering their names. (For instance, the default site that Debian provides is really named 000-default, to really make it most likely that it'll load first.)