A follow-up for the sake of those who might read this later:

I went to and from Heathrow on Delta. I went over from EWR. There were 80 open seats in Coach on the EWR flight (First was full) while the two JFK-LHR flights were showing nearly full. Coming back, I went to JFK. All three of the LHR-JFK flights were nearly full. But I was able to get on the second flight in Coach (First was full).

Earlier in this thread, it was suggested that I ask to be listed for the return flight prior to leaving NYC. I asked both the ticket agent and the gate agent in EWR if I could list for a return flight. Both said this was not possible.

Something to keep in mind leaving London; If you pay the taxes and are listed for the 10:30am flight (for example) and ultimately, you are left at the gate because the flight goes out full - you'll have to exit security, go back to the ticket counter, have the taxes refunded and start the process over for the next flight. In other words, you can't roll from one flight to the next. You are paying the taxes and being listed for one specific flight.

Overall, if was very easy. The Delta gate agents and crews were very friendly and accommodating.

Thanks for the ride!

Tipsy