Originally Posted by craigthemif

There is certainly no harm in having a valid ESTA at all times. It's only roughly 10 quid...


But IMO, flying a short Upper Class flight to JFK, over-nighting there (perhaps at your own expense) and continuing on via DL (mediocre US F presumably) would be a far worse experience than accepting the 75% refund (or an even better deal involving VS vouchers or miles), the PE seats and hopefully crew willing to let you spend time at the UC bar or otherwise make up for the downgrade.