Also, cheapest award levels to EU require a roundtrip booking for most markets. You don't need to book the same cabin in both directions to qualify for cheaper roundtrip award levels. There are also significant differences between different markets with award levels generally correlating to fare prices. There are currently $2900 roundtrip D1 fares on BOS-AMS in the Fall and you can see there is also cheaper D1 award pricing on this route.