There are many synonyms to replace the phrase "sitting pretty". The phrase implies that someone is in a good position, perhaps financially or in terms of power. Some other phrases that also convey a sense of comfort or advantage include "riding high," "living the dream," "on top of the world," "cushy," or "coasting." Additionally, one could say that someone is "enjoying the fruits of their labor," "basking in success," "living the good life," "lounging in luxury," or "leading an ideal lifestyle." These synonyms all capture the idea that someone is in a comfortable or highly advantaged position.