I've done just one transatlantic, and it was westbound. Hopefully, someone will come along soon and give the eastbound perspective.
In our case, it was a crossing without any ports of call. It was 6 nights, and as there was a 5-hour time difference between Southampton UK and New York US, we set our clocks back by one hour before going to bed on 5 of the 6 nights. I enjoyed having an extra hour on these occasions... I could go to bed a little later than usual, wake up a little earlier than usual, and still have a good night's sleep.
There were many activities during the day, from sedentary to active. I never became bored on this crossing. At the same time, I never felt rushed to do anything.
Which ship and itinerary are you considering?