Not sure where you are located but if you want to call it international but puerto rico would be cheapest. Also Mexico, Central and South America. this is all based on flights out of ATL.

Its fairly accurate but you can use the buddy pass calculator on travelnet. A quick look has most areas in Europe between $400-$500, $300-$400 for central america
A big part of cost is the exit taxes that are charged in most of europe.

Aisa will be between $650-$750. A lot of the time a confirmed seat is only $100-$200 more so you have to decide if (hopefully) being up front is worth possible delays getting stuck at a connecting airport.

Tony