Wrath of Kahn: The best compliment Kirk can come up with for his best friend, who vocally prefered Vulcan culture to human culture and consistently decided to embrace that part of his heritage rather than the other, is "Of all the being I've met, he was the most human."

Undiscovered Country: The Klingons, particularly Azetbur, actually vocalize discontent at the human-centric outlook of the Federation as one of the reasons they aren't exactly thrilled to take aid or alliance. The scene is played for laughs.

There's a definite edge of -- I'm not quite sure I'd call it racism, exactly, but definitely a kind of imperialism -- to the Trek humans. They're benevolent about it, but they're definitely convinced that their culture is the right one. It's a species-wide character flaw that would have been interesting to play with. I Roddenberry may have been leaning that way toward the end of his career, but, well, he's dead.