I do believe it's an enormous difference if you are just a guest at Balmoral (like top politicians) or if you are family.The queen's cousin Margaret Rhodes wrote only lovely things about her stays at Balmoral, how she has been pampered by staff and enjoyed herself enormously when being together with the Queen and her family. If Catherine has any questions there is William to answer them. She can always turn to him when she is tired or bored or want to do something else and nobody will mind if William says: Dear family, Kate and I need a bit of time together, maybe even get some rest before dinner.... On the contrary, I rather think the queen will be delighted then...