My site allows people to create free websites and provides them with a subdomain link to their site. For example, a user bsmith will end up with a site at
bsmith.example.com, and pages like
Obviously, I want my main site example.com to get as much SEO relevance as possible, but likewise I would want my users to have some of their own. I've created canonical URLs that follow the pattern
I have roughly 100k pages that follow this pattern, but is this the best idea? Is this diluting my main site, or strengthening it? I also offer a premium, paid service. Would there be any reason or benefit (to the users) to point the canonical URL specifically to their site instead of the main site, if they're a paying member? I can also support top-level domains, so would it make more sense then?