I just had the best start in ANY game of EUIV of my entire 2.000+ hours of gameplay. Indeed, maybe one of the best I even heard of:
I was playing with one of my all-time favourites: England. Everything was normal, I managed to ally Castille and Austria (Savoy and Britanny too, Portugal starts as my ally) to crush France. While I was preparing, Burgundy attacked the BBB; I let they tire out each other and then invaded France. They were crushed, France lost half of its provinces to either conquest and annexation, liberation of vassals and revolts. Meanwhile Burgundy grew into a monster by eating smaller HRE nations and I gained a PU over Austria out of the blue and then when I looked in detail I saw that the Lancaster dynasty had expanded the Castille and Aragón (in PU). My War of the Roses had lasted less than six months with a glorious Lancaster King that was something like 5/6/2. That happened while I was fighting the French and my terrible heir was replaced by an even better king by the event of the Tudors. We attacked Burgundy, as it had one minor too many by declaring war on Aachen which the HRE Bohemia answered at last. Both wars at the same time destroyed Burgundy, leaving it split into four parts and losing their overlordship over Holland and Flanders.
Then, with the help of Austria I forced a PU over Castille (and Aragón as a consequence) and when the war was over I proclaimed Great Britain (I have been slowly absorbing Scotland in the interludes between my wars). As the war ended I picked up a mission... Force a PU over France while Portugal has a weak heir with a weak claim to the throne... A Lancaster throne.
Also I have 6 provinces between colonies and full-fledged pronvinces in North America and 4 in the Caribbean and I'm allied to the HRE Bohemia. Welcome to the year 1530.