Carrie and Big in the "The Big Time". You know it shouldn't be, but it is. Big kisses her:
Carrie: Fuck you. (He continues to kiss her). Fuck you. (She kisses him back). Oh, fuck me.
And in the aftermath of the above the crown goes to the other side:
Natasha: Yes, I'm sorry about it all. I'm sorry that he moved to Paris and fell in love with me, I'm sorry that we ever got married, I'm sorry he cheated on me with you, and I'm sorry that I pretended to ignore it for as long as I did. I'm sorry I found you in my apartment, fell down the stairs, and broke my tooth. I'm very sorry that after much painful dental surgery, this tooth is still a different color than this tooth. Finally, I'm very sorry that you felt the need to come down here. Now not only have you ruined my marriage, you've ruined my lunch!
It gets even better when around "I'm sorry he fell in love with me" the self-absorbed Carrie smiles, apparently thinking that Natasha really sympathizes with her losing Big — only to realize a moment later that no, it's a "Reason You Suck" Speech.
Natasha gets another little moment. After Carrie puts her into a cab following her fall down the stairs, Natasha quickly reaches out and locks the door so that Carrie can't get in the backseat with her. Bridget Moynahan apparently ad-libbed that bit.
Carrie dealing with Kyra the judgmental mother in the end of "Woman's right to shoes". Especially as Kyra had the nerve to initially refuse to pay for Carrie's stolen shoes, which Kyra made her take off, on the grounds that "we shouldn't have to pay for your extravagant lifestyle", even though the woman has three fucking kids Carrie bought presents for in the past.