The important thing to know is if your state forces the manufacturer to cover emissions related component up to a certain mileage. In California, the law is that they have to cover them up to 150,000 miles. So that is a warranty unto itself. That covers certain expensive components related to the hybrid system.
But, not everything is covered. So I recommend looking first into state mandates and then what is NOT covered by the 3 year/36,000 warranty.
That should give you enough info to purchase the warranty you need. Hope this helps.