My dilema any help?

Hello to all. I am about to design another site in Drupal for a client (I am not charging, as it offers me good practice) The name of the organization I am doing the work for is Junior achievement. It's a non profit organization that introduces business practices to school children. And, once a year different Schools forms businesses within the program. The client then, wants EACH business to have a special part of the site, where they can log in and post information pertaining to their business (that visitors can see, such as mission statement, Vision ETC) and memebers of the company can discuss "internal matters" such as materials, production etc etc (visitors won't be allowed to s ee th is). Any suggestions on how this can be done? Priliminary brainstorming led me to organic Groups, but I am not sure how this should be implimented. Another pseudo solution I came up with, was to make a new company as a "role" and then set permissions and let the SIte Admin add new company users.

Any suggestions as to how I may implement this?

Thanks in advance.