It is always good time to burn when airlines temporarily lower the number of required miles. Air France and KLM’s Flying Blue program does this every couple of months. They just released the list for destination that they have at 50% discount for January and February 2012.
Thing to note is that you can book these one way and these are not only for originating from Europe. All the destinations are for both directions. The discounted awards within Europe are only from the listed cities. Other awards allow the origin/destination in Europe to be in zones 1, 2, and 3, basically meaning that these awards are valid from/to anywhere in Europe.
Thing to remember is that Flying Blue charges rather hefty taxes and fees for award tickets. The fees are mainly fuel surcharges (YQ) that they collect. Some think that award tickets should be exempt from fuel surcharges as they are part of the airfare. Anyway airlines continue to keep collecting them. As a result, it rarely makes sense to redeem for an economy class ticket. Also, there are no changes or cancelations of any kind allowed on promo tickets. You either use it or lose it.
You can sign up for the Flying Blue account and have a look at the availability. I would suggest first trying to find availability for the long haul flights and work the connecting fights, if needed, separately. You can only book these using Flying Blue miles but they are partner with American Express. You can transfer Membership Rewards points to Flying Blue 1 to 1. Another option is to transfer SPG points. 20K SPG points transfers to 25K Flying Blue miles.
Here’s an itinerary that I was looking for myself. Nice quick hop to Buenos Aires for 50K Flying Blue miles in Air France business class. The taxes at 392 euros are on the high side.