A number of US cities are eligible for a 25% discount on economy award bookings in the latest iteration of Flying Blue.
The lowest prices should be available when flying out of Dallas as those are being advertised as being available for as low as 18,000 miles on Air France. I was able to find a one-way economy award from Dallas to Amsterdam for only 18,000 miles and comes with $81.10 in taxes and fees.
Other European cities can be reached from only 19,125 Flying Blue miles one-way.
Flying Blue will get a 25% bonus when you transfer Membership rewards from American Express. You could transfer as little as 15,000 Membership Reward to Flying Blue in order to get a one-way award to Europe.