I have enjoyed being client side project manager. I suspect it is because a major part of my job of it is reviewing projects against our own standard documents.
As someone who has read game rules for pleasure over the years, such a task is well trod territory in my synapses. Furthermore this practice has helped me quickly recognize potential grey areas in my documents, as well as play out viable interpretations.
In all, it has been surprisingly fun so far. But much credit must also go to my bosses who have made the commitment to follow the standards consistently, and also avoided overloading me with too much work, doing this type of work takes a particular type clear headedness to do well.