I recommend LiquidPlanner for hardcore project types. I know of people who use Asana, Basecamp, or Trello. Depends how sophisticated you want to get.
Do you want other teams involved to do that collaboration?
Does Marketo offer an in-house project management tool?
Do you have any recommendations for a tool that can provide clear direction on workflows between the communications, graphic design, product marketing and marketing automation teams?
I have used a host of these.
In addition, I've seen use of JIRA, and more recently Slack, but Slack is less sophisticated of a PM tool.
I come from the MS Project world, and during that part of my life was very regimented and needed strict dependencies and a tool that could intelligently shift timelines and adjust.
I have not seen such capabilities of any tools listed above, though my exposure is limited.