Amsterdam to New York is about 5,848 km and usually takes around 8h in the air. The track it follows runs over the North Sea, the British Isles, and the North Atlantic.
Over the North Sea the air is usually calm and settled. Nearer the British Isles and the North Atlantic the weather turns more Atlantic and the ride can be livelier for short spells, still firmly within the routine. This track threads jet-stream latitudes, so in winter you may feel a few minutes of light, choppy air high up; summer usually rides calmer.
A flight this long spends hours at a high, smooth cruise. Even when one stretch is bumpy it is a small slice of the whole trip, and the aircraft treats it as routine.