Need suggestions on how to structure virtual fair website with Drupal

Hi. I need to create a website for an organization that handles virtual events, like an online version of real conferences or fairs. The website is structured around virtual spaces which can be:

Fair lobby (which can contain one or more pavilions )

>Pavilions (each pavilion can have one or more virtual rooms below)

>>>virtual stands

>>>auditoriums

>>>Lounge rooms

One important aspect of the website is that each virtual space (lobby, pavilion and virtual room) must have its own design, usually a picture of the real place with links or block contents, just like these images in this similar product: link( http://6connex.com/virtual-destinations/ )

In each virtual space, fair attendees can see news, articles, videos, images, take quizzes, collaborate in forums, chat with sponsor’s staff, see job opportunities, comment content. Usually they can see public information for each virtual space and need to register and logon to go further and answer quizzes and some other functions.

Each sponsor, responsible for one virtual stand or virtual room, will publish job opportunities, create chat rooms, open topic in public forum, send quizzes and analyze results.

Does anybody have any suggestions on how I could do this? I was thinking about using organic groups which can be themed, right? Or Groups could be used? Or any other option?

I'd really appreciate any help on this.

Thanks.