I prefer Ecclesial Balance over Church Supremacy. I don’t like having to pay the large tithes that you are locked into that way. And Ecclesial Balance still gives you decent piety and decent wealth.
As far as money goes, you can certainly spend many years savings in a hurry. Try a huge country like Germany and you will find that you have tons of money, but still not enough to raise ALL your armies for that long.
I tend to try out the different regions in my campaigns, and they all seem to play a bit differently. I’ve been playing the Italian area with Apulia lately, but before that I was playing a game that covered substantial parts of England, Scotland, Ireland and Greenland. Beyond that you have the Russian Orthodox powers in the East, France and Germany, Scandanavia.
You can’t play Muslim countries in the stock game but there are mods that allow you to do so.
As far as marriages, you should click on the shields of some of your neighboring powers, and further off powers if you want, and look at their courtiers. If you find a potential wife amongst the courtiers, you can propose.
Generally, if you’re not proactive about your female courtiers, you will receive marriage proposals from other courts. You can reject those offers and try to arrange a more strategy marriage if you want though.
Playing as one of the Russian Orthodox powers can be fun, cause you have plenty of Pagan targets in the east. Like fighting Muslims, when you fight Pagans, you get the territories you take right away, rather than having to negotiate a truce. Plus most of the pagans are pretty weak.
Also, as one of the Russian powers, you will be on the front lines of the war with the Mongols that happens later. Unfortunately, the mongols have been disappointing the two times I’ve played late enough to see them.
With the mongols weaker than they were historically, the Muslims preserved there power base quite well into the late game in both of my favorite playthroughs, and they always seemed to have the perfect system of alliances, to make it hard to gain much ground.
I’ve seen almost all of Spain, Italy, Scandanavia and large parts of Russia held by the Fatimids, Seljuks and their vassals at one point in time.
My own Kingdoms have reached as large as holding England, Ireland, Scotland, substantial parts of Northern Africa, France and a few counties in Italy. I created a strange African Kingdom title. The game developers have come up with Kingdoms even for areas that never were Christian Kingdoms, so if you conquer large parts of the Middle East or Africa you can get these new Kingdom titles.
The problem when you are large is there are a number of events that can hit you hard, and you have so many vassals, that its hard to keep them all in line. And all of your vassals put together have more power than you do, so even if a majority of them rebel against you, they have the chance to wipe you out.
Plus there is an event that makes them disloyal and starts causing your empire to pretty much crumble. That event hit me three times in my last long campaign. But I had the pleasure of wiping out England permanently by the end of the game, at least as the normal entity of the Isles.
I enjoyed that because England had played very smart as an AI and several times declared war on me out of the blue and forced me to struggle mightily to keep Scotland and Ireland.
To me this game isn’t really about winning or losing. Its more like Sim Feudal Society. I don’t really care if I get the highest score at the end of the campaign, which is technically how you win. I have heard of a few incredible stories of World Conquest in CK. These are the best players of the game ever, way better than me, and even for them it is a huge task to try to conquer the world.
Unlike games like Civ where you gain more power and gain more advantages as you get larger, CK follows the historical cycle of societies where they become more powerful and larger but eventually crumble or get reduced in power due too bad leaders or just too many lands to properly keep a hold on.