Data Integrity Address information on Opportunity

How are global customers using address information on the opportunity keeping in mind the need for data integrity.

We track the location of each opportunity by Address/City/State.

Here is the use case:

1. Job in the U.S. looks like this.     

     a. Address 1 - 4445 Oracle drive     

     b. Address 2 - Suite 123     

     c. City           - New York     

     d. State         - NY

2. Here are the issues we are seeing.     

     a. How to control the data being entered in City.     

     b. How to control data being entered in State. - on the account object it is controlled by Country and then is a pick list. This works for account, not opportunity.