I appreciate clarification on national attitude and how it effects coalitions. On the third point, it has been my experience that in almost every game I play any great power bordering me eventually decides it wants all my stuff. In last week's Castile game France was my ally for centuries, then one day they decided they wanted Nevarra, then shortly afterward decided that, screw it, they wanted my whole country and declared me a rival.
I've restarted a lot of games due to sudden, inexplicable diplomatic shifts and it has conditioned me to prefer Quantity over Diplomacy, as it were. To that point and more on topic, the unique buildings I miss most are the War College and the Admiralty.