Intranet/extranet capable themes – user level control

HI folks,

Apologies were these questions to be a little basic. We met with our client this morning and were about to send across our shortlist of 5 themes from 150 business themes we selected. It was mentioned the need for Intranet capability.

The business model is office and virtual office space. The public site sells the services and then clients can login and will have access to different content/menus and account information.

Is this something that can best be done through a WordPress Theme (can’t seem to find any) or a plugin ( not sure where to start in finding these) ?

Totally lost and need to get an answer back to the client today so any help you can offer is appreciated. We have a lot of experience with Joomla so there is always that option were WordPress not be able to handle this.

Thank You

Sam