We have incident where we have following process.

We have following state for incident.
1.New
2.In Progress
3.Pending Customer
4.Pending Information
5.Customer Update
5.Resolved
6.Closed

Incident Process till Close1.New created incident in New State
2.Fulfiller should ACK the ticket by clicking on ACK ui action and incident should go in "In Progress" state.
3.Fullfiller can change the state to Pending customer to get information from user i.e. caller.
4.When user i.e. caller send the information then incident state should changed to "Customer update"
5.Fullfiller then change the state to In Progress.
6.After resolving ticket fullfiller can change the state to Resolved.
7.Fullfiller can cancelled the ticket when it is in In Progess.
8.Fullfiller can Reject the incident before Acknowledgment.
9.Fullfiller will not close the incident, to close the incident we have schedule job which will run daily.
10.Incident Auto Close schedule job will close the incient which are in state=resolved the update date is less than 5 days of current date.

Note:

User can Cancelled the ticket by changing the state=Closed and closed code=Cancelled
User can Reject the ticket by changing the state=Closed and closed code=Reject

Close Code and Close Notes:
When Incident changed the state to Resolved or Closed , Close Code and Closed Notes are mandatory fields.

Close Code is choice field
Close notes is String field.

Close Code and Close Notes fields having more specific details about "Why we are closing the Incident."

SLA:

Responce SLA start when incident is created and stops when Incident Acknowledged (If ACK_Time and ACK_By field has value then incident is acknowledged)
Resolution SLA start when the incident is in "In Progress" and stops when incident is Closed and pause when incident is in one of the state i.e.
Pending Customer, pending information, customer update and resolved. 

Incident Priority:

Priority field is always readonly and it is depends on urgency and sevirity fields using datalooup

We have one client script i.e. if the caller is VIP, then the priority should be P1 using client script.

Incident Assignment Rules
We have assignment rules for setting assignment group as per Incident Category and Incident Subcategory