We were on the Magic last November 3 and drove in from South Jersey. Our PAT was 11:30. We took the NJ Turnpike to the Lincoln Tunnel. Traffic wasn't too bad until we got near the cruise terminal. If you are unaccustomed to traffic, it's going to be really bad the whole time you are in NYC. As we were heading north past the cruise terminals there were plenty of vehicles. Several traffic lights held up and controlled the flow of traffic. We saw a few police escorts trying to go in the same direction with their sirens blaring. Like it was really going to do any good. I kept telling my wife the sirens were saying 'welcome to New York City', but she remained unconvinced. The actual route is not that difficult. Basically, it is go through the Lincoln tunnel in the left most lane, go up a couple of blocks, make a left, go a couple of blocks, make a right, get in the left lane, continue on until past the cruise terminal as you need to make a left into the cruise terminal from the north end. There were numerous police directing traffic at each end of the cruise terminal. Bring up the route on Google Maps or Waze. Also map your way out to get an idea of where you need to go. Getting out was just as easy.
If you need to drop off your luggage take the middle ramp, it is well marked, drop off your luggage at the proper pier, continue ahead, exit the terminal and head back to the north end. This time take the ramp to the upper level and continue to DCL parking. If you can wrangle your own luggage you can head directly to the parking when you first enter the terminal. Park and take the elevator down a level to where the porters work. We travel with an ECV so we dropped off our luggage and circled back to the upper level to park. There is a ramp at the south end of the cruise terminal but it is a down ramp only. You will use it when you leave.
Re: leaving NYC - On our trip it was cold, and got very cold once we were heading down the river. We wanted to get as many photos as possible. We were exchanging texts with our daughter who was watching the ship on the PTZTv cameras. When the ship got close to the Verrazano bridge I took some flash photos, four in a row, with my phone. Our daughter was able to see the flashes on the PTZTv camera.
We had expected rough seas in and out of NYC. It wasn't as smooth as cruising around the islands, but not rough at all. I understand several cruises a week or two prior to our trip had a rough go but they were headed north from NYC, and there was a storm in the area.
An EZPass transponder will help too.