Will be flying into Newark. What's the best/least expensive way to get 4 of us to Midtown?

Taxi, no question, for 4 people.
Do a search on this forum with the word "newark" and you should find much discussion/information about this
Hope this helps

How light are you traveling?
You might take the taxi to Newark Penn Station, then take the PATH Subway to Manhatten for $1.50/pp or NJT Train for $2.50. That's about rock-bottom prices I can think of. There's a NJT Bus, called Airlink, that goes from EWR to Newark Penn - I think for $4/pp

The least expensive way is the New Jersey transit bus (#302) to the Path train. Bus is $2.50, Path, $1.50. The last stop on the PATH is 32nd and Broadway. Unless you are staying in that area a taxi or the subway would be necessary to get to your destination. Subway or bus is $1.50 a person. For the various transportation options go to www.panynj.gov. Click on airports.

I would not take the PATH, Airlink, etc. I did that once and vowed that I will never do it again. The connection between PATH to Airlink was confusing and no one seemed to know where to make the connection. The wait for the Airlink was long and I almost missed my flight. For 4 people, a yellow cab will comfortably take you to Midtown for about $10/person. Spend a few extra dollars and take a cab!