What is the best tour to go on?

I am planning a day trip to NYC from the Poconos in May. It will be me, my husband, my mother-in-law and 4 yr old son. We are looking to do a tour. I have looked at private tours (too expensive), the walking tour with the Real New Yorker (mobility issues) and a hop on and off tour. I looked at the OnBoard tour which I think might do pretty good. What tour is best for a 4 yr old and a mobility issue mother-in-law. I want to see as much as I can but not spend an arm and a leg. Main things I want to see is the Statue of Liberty, Ground Zero, Times Square. I want to visit the Museua of Natural History and the Empire States Bldg. Anything else I NEED to see? Thanks in advance for any suggestions. Also, if I could I would like to park outside the city and ride into the city (maybe by train, Grand Central Station?) Don%26#39;t know since this is my first visit.

What is the best tour to go on?

It sounds like the answer to your question is NO tour. A 4 yr old won%26#39;t have the patience for a tour except a hop on/off one and it sounds like MIL won%26#39;t do very well with that. For the things you want to see/do, you can do it on your own. Take the free Staten Island ferry to see the Statue of Liberty without a commitment of too much time. From there it%26#39;s not a far walk to the WTC which at this point is just a construction site but you can visit St. Paul%26#39;s chapel. Then head uptown to the Mus. of Natural History and end the day in Times Square. I would suggest Top of the Rock instead of ESB, but that%26#39;s up to you.