Great job on the plugin however I've notice the following bugs with regards to the plugin capturing the State form both billing and shipping.
1. The plugin captures the number in value attribute associated to the state from the billing (e.g. 14,15,16) and not the actual name of the state; Which is then displayed in the email sent to the customer.
2. When same as billing option is checked/selected The plugin captures the placeholder text (e.g. state)and not the state from billing then displays that in the email sent to the customer.