Suggestion needed - where to visit this weekend for 3-4 days

Hi Friends,

We are planning to visit some place this weekend for 3-4 days with 4 year old as we both can leave from work, but I am unable to decide the place. Earlier we planned for Vegas or Chicago but tickets are very expensive because of spring break in school, so now we are planning to visit some where near by to NJ, NY, PA

As of now we have shortlisted below location but unable to decide if this is right time

1. Boston (and cape code)
2. Upper side NY
3. Baltimore (not sure if this really requires 3 days)

We are not historical buff. We have already been to DC and Niagra.

Can you please share your view on these places or suggest places other than above.

Thanks in advance
Priyanka