Estates are indeed really fun, and useful if you manage well! Gotta understand that influence/loyalty is mostly static (over time) and only big ass events and giving out the maximum-est provinces to them can make them very profitable (at the same time, not, since it increases autonomy; also events can force you to completely fuck up an influential group!).
I have been participating in a stable MP game that is nearly over for the past two weeks, I will post a european-centric animated gif of it in the next days (when its done), in political mode (and other modes if people suggest something that can be done!).