Hello David 

It’s great that you’re planning to onboard multiple teams to workspaces. However, there are several features you may overlook if you opt for a business workspace, please read here to know more about this 

Here are my 2 cents. You should create a workspace if you are looking for the following. 

Isolation of data : If you want segregation of data to protect sensitive information between the workspaces. 
Separation of configuration : If you want to build walls between the configuration of various departments with in the organisations, Now that with sandbox in place for each workspaces makes the life of the admins easier. 
Delegation of administration : If you have want to have separate admins for different business unites with in the organisation so that they can make their own decisions without conflicting others. 

Reduced operational costs : Moreover, opting for workspaces can lead to reduced operational costs, as you'll spend less on agents due to the different licensing model for business workspaces.

There might be 2 scenarios which you might come across

1. Bringing in new teams by creating a new workspace altogether. 
2. Splitting the primary workspaces into multiple workspaces. 

Scenario 1 is relatively simpler to set up since you'll be starting from scratch, whereas scenario 2 could be a bit more complex. In the latter case, you might need to transfer some configurations from the primary workspace to the business workspace, which requires additional effort.

Please check with your Account Manager or Customer Success Manager, they will suggest you the best approach for both the scenarios depending on the configuration. I will let others also add their thoughts. 

Hope this helps!