A 157K award is just a combo of a DL over-the-water CSV820 award and a VS over-the-water CSMG750 award (VS LHR-JFK + DL JFK-PIT). It doesn't have anything to do with a roundtrip purchase.
I was wondering about that. I didn't actually click on the "157Ks" to investigate the actual details of the flights.
FWIW, there's currently some pretty cheap COACH roundtrip awards to Europe. BOS-LHR is available for 32K roundtrip.
Sorry, I don't understand your lingo. What is this "
COACH" thing you speak of?!?