I've done Kennedy and Newark several times, not very difficult to do beyond the costs. Haven't done LGA, but it'd be fine too. Kennedy is probably easier, but remember that there is no FBO there ... just the Port Authority parking and money collection building ... though they do have nice bathrooms and a phone there. Taxis are readily available and the PA will van-ride you to/from the terminals. Terminal parking buses lead to the subway, and from there anywhere in the city is in reach.
If you want to do Class Bs and don't mind going a little further, PHL is not a bad trip and on certain days of the week Atlantic Aviation offers pretty steep discounts on Avgas, call them to check. IAD would be a good trip, Piedmont is a good FBO there, and after the 15th you can check out the Smithsonian annex there.
If you hit BWI, ask the Signature desk about an Italian place in Linthicum ... just a few minutes drive away, Signature recommended it the last time I was through there, and it was pretty good. (Of course, I don't remember the name of it now.)
There are on-airport restaurants at Frederick (FDK, home of AOPA) and Barnes (BAF) in central Mass.
Enjoy the flying!
FL270