Things to do/stay outside New York

We are visiting New York in July for 4 days but don`t want to spend the whole time in the city. Does anyone have any ideas, either North or South of the city, where we could stay ,beach or inland location, but still easily travel into the city using public transport?
Thanks.

You could take the train from Penn Street Station towards Boston. there's some beautiful countryside outside of New York. There's some major towns along the way so you could get off after an hour or so, and come back.

Take the Trenton bound line from Penn station and visit Princeton and/or eat lunch along the Delaware River.

45.