My Poland is doing great after several aborted games due to splintering after a few rulers. I've found after restarting a few times that instead of going after the heathens to the North for some coastline immediately after they are distracted by fighting each other, Denmark, or HRE as I had been doing, it's much safer to ignore them for a few years and work on plotting against, assassinating, or marrying my dynasty to the heirs of the other Dukes of the kingdom of Poland in order to replace them with Piasts.
The heathens are powerful enough to resist anything short of the HRE since they call each other to assist against a holy war due to a common religion. Denmark or Sweden or HRE eventually conquers them if you wait too long though and then Poland proper has no coastline which is a huge disadvantage.
Once Poland's Dukedoms were under the control of Piasts it made it much easier to keep succession troubles from breaking out. So far I've only had to assasinate two relatives who's father was a well landed Piast I married to a Princess heir of Croatia. Unfortunately the first two male children's liege was the King of Croatia so they would have taken several dukedoms and at least a third of the counties of Poland with them upon succession. The third male child owed it's allegiance to the ruling Queen of Poland so his brothers both died choking on their blood not knowing the identity of their killers. (save scummed though)
That gave me parts of Croatia and I remembered I had married a relative of the bloodline of Croatia to the Piast heir to Poland. That allowed me to declare war for the Croatian family in law for the throne. I won as Croatia had been reduced by Hungary and rebellions and placed my daughter in law on the throne with plans to have the Piast offspring take the throne eventually. Then I was told I could Usurp Croatia as I owned exactly half the counties so I did that instead with a quickness and now my character is the Queen of Poland, Croatia, and Lithuania. The same Queen had formed the Kingdom of Lithuania after taking the territory from the independent heathen tribes. She also has 1/3 of Italy from the first King from 1066 marrying Matilda the Duchess.
The same Queen's Italian holdings were attacked by the Papal state and she won by sacking Rome and the entirety of it's county very early in her reign before she took Lithuania. The funny thing is she is Catholic and her title is 'the Holy.' I was hoping I could arrest the Pope but all it let me do instead was force him to pay me around 1100 gold and I built a new castle holding in Krakow with it. Krakow now musters 1-2k troops by itself thanks to that. Too bad I couldn't have become Popette though hehe.
The Muslims of Sicily at some point took all of Italy and Sicily up to Spoleto (which I own) and Rome (which the Pope has). Finland is owned by Islamic Bulgaria so I'll be deciding which of the two will be her likely final conquest. After that her heir is a much weaker individual who apparently made poor choices after being raised by her, as he has a lot of negative traits I didn't pick.
HRE is even stronger than at the start, Rus is still split between Novgorad, Kiev, and Galich. Far eastern Islam is surprisingly strong. Hungary is also stronger than at the start and is probably roughly as powerful as me so I think I'll make an attempt to take it over at some point when I'm the Queen's heir as it's between Croatia and Poland and controlling it would consolidate 2/3 of the distinct areas I control. Then it's the HRE's turn but since that is Elective I have a feeling it will be tougher than Kiev and Novgorad and such so I'll revisit that decision then. If it splinters I might consider supporting the rebellious vassals but those 10-15k armies I see constantly on the move in the HRE gives me pause as I can raise about 8-9k through vassals and have enough income to support a few cheaper upkeep mercenary bands to boost it to maybe 12k max.
Oh, somewhere in between all of that she declared war on Denmark for the entire Kingdom in support an aged female courtier of Ylving at her court with a claim on the throne. I was hoping the new Queen would die without an heir and somehow I'd get the throne, but all I got was a (more) friendly ruler once I'd won. Well, that and tons of loot.
Oh, funniest thing that happened was in the 2nd Crusade for Jerusalem. It ended in about two months successfully and an Irish duke became King of Jerusalem and has yet to be forced out.
This is after the first crusade was an utter failure and waste of men that took years of total Muslim dominance to finish.
Also, yes you can ignore crusades but you take a minor respect hit with all (I think) members of that faith for 'not crusading'. It might only be members of the clergy.