You will have to pay but it depends how fussed you are about which seats you get.

It's a very heavy CW route so you won't have free choice. If I were you I'd choose a 747 service on the way back, and pay for seats on the upper deck, e.g. 62AB. When you climb the stairs and get up there, you won't regret it . It also takes a little stress out of ensuring you're logged on at exactly T-24 hours to try and grab the best seats at that time - particularly if your NYC trip is a holiday.

P.S. I love the fact your BAEC status on your profile is 'BA Brown'