I have created a Nintex form and set it as a content type - so that the form can go into multiple sites and I only need to maintain the form in one locations and sites will automatically be updated with changes made at the content type level.
Now I would like to create a workflow - in the same idea - manage the workflow once (as the form is)
There does not appear to be a way to create a content type workflow associated with the form. - it appears to only offer OOB SharePoint workflows.
I then started looking at Site workflows - but I don't know how to get the Site workflow to cycle through lists on multiple subsites.
Has anyone done this successfully?
Not sure which version of Ninex Workflow you're using, but try looking into reusable workflows. Resusable Workflow Templates allow the workflow to be used on a content type, list, or library through the default SharePoint Workflow settings option.
Here's a link to the Nintex Workflow 2013 documentation: Reusable Workflows