You are of course aware of the universal visa requirement - called "ESTA Registration" in order to get around international treaties ? For reasons that may be obvious,I advise you, keyplus, to complete this for all travellers BEFORE making any travel arrangements, ensuring that there is no obstacle for any of you to get onto a flight at the UK end, don't risk that kind of disappointment.
There is a lot to see and do within the US and you are unlikely to meet any Americans who are anything but friendly and gregarious, but I find the visa requirement (and going through US immigration) so objectionable that I have stopped going there (I have relatives there and have been many times to various parts). Have a really good holiday, best wishes.