Well, I do admit it's difficult to pick out just one passage/section out of the book. I would have picked most of the ones you picked, as they're really hillarious. I like this passage, both because it's funny but also it's an unusual moment in which we suddenly see Elizabeth from Darcy's perspective.
"I cannot talk of books in a ball-room; my head is always full of something else."
"The present always occupies you in such scenes -- does it?" said he, with a look of doubt.
"Yes, always," she replied, without knowing what she said, for her thoughts had wondered from the subject..."
Exquisite! A few skilful strokes of the pen, and you have it!
And now to my new question:
Pride and Prejudice Question 19
Jane Austen is often praised for her knowledge of human character. If you had to choose a character in P&P who was the most “human” in the sense of being someone you could easily meet in the world today (and isn’t typical of a particular time or period), who would that character be and why?