...the Doubletree Times Square is a great choice for families when staying in NYC,,,I'd also recommend the Marriott Residence Inn, the Embassy Suites (though downtown location is a bummer -you want to be midtown), or the Rhiga Royal for all-suite comfort.
...cab prices run about $70 (incl tip) from the NewarK Airport area to midtown Manhattan....the best bet by far is the $12 ride on the AirTrain to Penn Station (take NJ Transit trains - and remember that there are TWO Penn Stations - one in Newark, you wnat the one in NYC!)
...NYC can be very expensive, but I feel most of the very best stuff to see/experience is free or inexpensive....hotels really are difficult to find good deals on - if you travel at all and have accumulated points on the Marriott/Hyatt/Westin etc... frequent stay programs - by all means, NYC is the place to redeem those free nights!!!!
....when in NYC, grab a gyro and pretzel for lunch from a street vendor - they're delicious and the full meal will be less than $5! Enjoy!