I will let others chime in here but highly recommend working closely with your Customer Success Manager on creating an adoption strategy for you specific use case.
Here are some quick tips:
1.) Start simple and eliminating unnecessary modules, features, and actions from the UI
2.) Ensure all users understand how their data rolls up to management and the executive team
3.) Make sure all users receive enough training and have a channel to ask questions related to not just Clarizen but your specific processes and use cases
4.) We have a great tool called the User Adoption Dashboard. This will let you easily see who your most and least active users are so you can prioritize who you spend the most time with: https://success.clarizen.com/hc/en-us/articles/212185218-How-to-Create-a-User-Adoption-Dashboard