It "costs" about 25,000 miles for a domestic round trip, 50K to Europe, and 80K to Europe in business class. There are only a couple of award seats on every flight, and some flights have none, so it can be difficult to redeem awards. When you consider these difficulties, the awards are worth less than they otherwise might be. If you fly alot and achieve elite status on an airline, the value of the awards increases because you can redeem awards for first class travel at attractive rates.