multi-site, buddypress, other?

Hi

I have a wedding site and would like to give my visitors the opportunity to create their own personal sites… either for blogging or sharing wedding info for their guests.

I’m not very savvy with “the wordpress” so I want to go with something fairly simple and easy to manage. I think either buddypress or a multisite setup would work.

I’m guessing I want to make it possible to nofollow some (or all) user sites, just in case their content isn’t great.

Does anyone have any suggestions on what’s easier or better.