Since this was a business led decision, I wanted to make sure we weren't going to detract from our current customers experiences should they decide to stay with the free plan.
We knew that a majority of our users had a single workspace, with a smaller group of users have 3 workspaces on average. After speaking to customers to learn more, I was able to confirm that the Workspaces feature was primarily used by our power users and that treating it as a paid feature would not create too much of a negative impact.
For design exploration I considered multiple paths starting with exploration of how the folder and project structure could be exposed through the navigation.
Then I moved to a rough sketch of a version where the user could see this interactive list of folders and projects:
However after reviewing this with the team we all agreed that this was putting too much information in front of the user and could be overwhelming. The business team had also given further guidance about how we can draw the lines, features that were primarily used by Power Users like Folders and Workspaces would be downplayed.
For my second iteration I prepared a more traditional sidebar:
This sidebar was more closely aligned with the users workflows and our current IA. The side bar was also collapsable for users who wanted to see more projects on screen. I received very positive feedback from the team on this pattern.