Delta Comfort+ is the way to go. We just used them a couple of days ago for our trip to Paris and it was stellar and NO CHANGES during the six months booking to flying time. We will use them for our return from SXM in January

I will admit that if I was in the MIA area I would give the n/s AA (gulp) a try.....N/S is a major plus. We gave up on the JB n/s return to BOS with the extra room price approaching $900 ONE WAY