We provide specific examples to demonstrate the capabilities, and to allow copy/paste configuration. We don't provide a combined one (yet, anyway) as everyone's requirements are different.
Having said that, it is possible to create a workflow whose flow depends on user input. We actually do that for Web Content Management - the submit process allows the user to select serial or parallel review etc.
At a high level this is achieved by defining a task that collects the relevant information (e.g serial or parallel, assign to person, group or pool, the person(s), group(s) etc). Then in the process definition use <decision> nodes to redirect the process to the next appropriate state based on the information entered in the task.
Take a look at config/alfresco/workflow/submit_processdefinition.xml for an example.