In chapter 1 of The Great Gatsby Nick Carraway echoes the words of his father
"Whenever you feel like criticizing any one.. just remember that all the people in this world haven't had the advantages that you've had."
Nick explains that, as a result, he has maintained a low profile in terms of his own emotions, maintaining a distance when emitting an opinion, if any, and being accused as a result of trying to be overly politically correct.
However, Nick also admits that the result of his reservations have made him more conscientious of the "nature" of people, as he spends less energy criticizing and more depth of analysis in trying to figure people out; how they are, why they are the way that they are, and what motivates their actions.
This being said, Nick will probably be with anyone the same way he was with Gatsby: he would allow people to manifest themselves to the fullest without hearing a word of reproach from him. Nick is not smitten by the rich because of their opulence, but more driven to examine their flamboyant behavior. When Nick witnessed Daisy's proneness to indiscretion his only complaint was for the sake of the reputation of those involved; at no point did he condemn nor condone her cheating, nor Tom's, nor Gatsby's lies, even..he figured everyone had a reason to behave the way that they did and such reasons are none of his business.
Therefore, Nick is the type that will simply be the listener and observer. He would follow along without switching his opinion of whoever is in front of him. He would focus more on temperament than on choice making, and he will always remember the words of his father.