I’ve used Quickbase for managing projects + clients, and although the initial setup may take some time, I think it can definitely help organize your projects and clients. You can assign tasks to different people (including clients, they can either access the system with their own admin password or an email can be sent to them). You can also rank tasks in priority, even put your billing information through as well, not to mention generate reports…etc. It proved to be quite useful in organizing multiple clients, staff and projects.

Another client management system I’m fond of is Active Collab – you can add projects there as well with their own set of tasks and it works as an awesome checklist system. I’m pretty sure you can arrange a different admin access for clients in that as well.

Cheers, let me know if any of those work out!