Requisition Approvals

We are looking at updating our requisition approval workflow. We currently use route controls (origin based) with monetary level approvals via AWE. We are wondering what others use as a basis for approvals. Our requisitions can have multiple department codes but we are looking at this as a possible driver. How do you route your requisitions for approval? Do you base it on monetary and a secondary approval criteria? If so, what? Do you use route controls? Application Class? Other, what? Thank you for your time.