Well, directs to BCN are from EWR or JFK. PHL doesn't have any. EWR is on United, JFK is Delta and AA. All have some alliance codeshares, but those are the actual operators.
If all you have are US miles and there is award inventory now, I'd say just book a partner award and fly United.
Do you have any extra time? Remember the US award chart allows for north asia in J for fewer miles than europe. Can you do your cruise as a stopover en route to asia, even for a couple of nights?