Just to close the loop on this question thought I would let anyone who might be interested what we decided on (I always like finding out what people end up doing when they have posted questions on message boards that I have answered!)
We are going to see How to Succeed and RENT.
How to Succeed based in part on the feedback that it would be family friendly, fun 'Broadway musical' style show, but also that the casting - in particular Daniel Radcliffe - would mean that it would be an experience that the kids in particular could only get this specific year and only by seeing it in New York. I ended up getting front row mezzanine (discounted) tickets so we are good to go on that!
RENT - I did listen to the comments on 'appropriateness for a 10 year old' and stepped back and thought about it, and decided that while there were possibly uncomfortable or challenging themes on sexuality, drugs and lifestyle, that there were also themes of community, self-expression and 'finding family' in sometimes unexpected shapes. I am comfortable that we can talk about some of those themes before and after seeing it as required. I was particularly interested to hear from those of you who had said this particular show had made a strong impact on you the first time you saw it and think it could be a good artistic and educational (although that is really too dry of a word for what I am trying to get across!) experience.
We will see those early in the week that we are there, and if the family wants to, have left a gap later in the week where we could look for last minute tickets for something that catches our eye - if the family loves the idea of adding another show!
So thanks to everyone for their input