Looking at a trip to the above, 6 nights 7 may in NYC then 5 nights 13 may in Boston. Is there any special events going on?

What kind of events?

There's always a million things going on in NYC and Boston.

You didn't say when you are coming. How can anyone tell you if there are any special events going on?

I think the OP means he is thinking of:

NYC May 7th for 6 nights, then
Boston May 13th for 5 nights

FYI, May is a very busy time for hotels in Boston because it is graduation time.

Boston University commencement is Sunday 18 May 2008: Book a hotel right now, if you still can.

Boston in May is always mobbed due to numerous college graduations. Book a hotel ASAP - as price will only tend to go up.

(You might be better off reversing the trip - but you would have to check the various commencement dates for the many schools in Boston.)

As for what else is going on - I'm sure a lot - but it's very early to tell.

For NYC check out New York Magazine website - which lists hundreds of events by date and type - when you get closer.