Carrie = NF, taken to it's most exaggerated "self-searching" form
Samantha = SP, in the most XXTREME version of an SP possible (unsurprisingly ESTP, and a VERY over-the-top ESTP at that)
Miranda = NT, in her head to the point of not having sex with her husband for long periods of time, apparently...very extreme
Charlotte = SJ, in the most stereotypical, uptight, conservative form possible
The archetypes made it entertaining and was something everyone could see since the personalities were extraordinarily clear human archetypes. You know, that's surely on purpose...it's easier to "escape" or "lose yourself" in something that's a little bigger than real life.