There is a great service provided by Google which is dead on accurate as far as the city is concerned. The problem with the time you're landing and the time you will be going into the city is the fact that on a weekday this will be a rush hour, so here are the better options:
- Take Airtrain to the E Subway Line in Jamaica and Take E train Manhattan/Downtown direction, which under normal circumstances will take slightly more then an hour to get to 8th Ave 23rd Street
- Sorry no Airtrain available so it will be a bus to Subway transfer which could be a pain with luggage but it will drop you off right in between the 2 districts on 23rd and 6th if you take one of the orange lines F or M. F should be faster since it's running express in Queens.
Newark Options 1 and 2 can be found through this link
- Option 1 - Bus to PATH. Take a bus from Airport to Newark Path Station and then take PATH to Newark changing at Journal Square Station for Path to 33rd street and take it to 23rd street station which is 23rd street and 6th Ave on the border of the districts.
- Option 2 - Train to Penn Station. Take Airtrain in Newark to the Newark Airport train station and then take Amtrak or NJ Transit to the New York Penn Station on 34th and 8th Ave, and then either walk a few blocks (they are short) or take E train Downtown direction for 1 stop to 23rd Street.
- Option 3 - Bus. Coach USA provides a shuttle that runs every 15 minutes from each of the terminals and takes 30 - 60 minutes depending on traffic to get you to NY Port Authority Bus Terminal from which you can take E Train or walk.
Of course there are always taxis or airlink services such as:
That you can simply board and they will drop you off where you need to go. Might be a little more expensive then Public Transportation but easy and more convenient.
As you can see most trips will take about an hour.