Has anyone had any success applying rationalist principles to Major Life Decisions? I am facing one of those now, and am finding it impossible to apply rationalist ideas (maybe I'm just doing something wrong).

One problem is that I just don't have enough "evidence" to make meaningful probability estimates. Another is that I'm only weakly aware of my own utility function.

Weirdly, the most convincing argument I've contemplated so far is basically a "what would X do?" style analysis, where X is a fictional character.