well, i think ive had a pretty good game as castille, with all of iberia, france, italy, north africa, egypt, heck the middle east, by 1220.
a few recommendations:
it may seem like a gay tactic, but kill the successors before you for the kingdom of leon, and then finally kill your brother. youll inherit all of leon, which will make the next step easier to pull off.
start taking apart the muslims in iberia little by little, and alliance by alliance, eventually you should control almost all of iberia. if aragon still exists, then you can just take them over or whatever. just keep in mind to control the richest provinces in iberia and give the poorer regions to your children and siblings
next, you can start taking over north africa via morocco and then sweep east. to help yourself early game, make kingships asap if possible since they will help your prestige alot. and early game, prestige is important for loyalty. also, whenever a muslim country asks for peace and offers something like 6000 or 8000 gold, TAKE IT, then immediately declare war (dunno how this fares in 1.01, but this is how i racked up about 100k gold by 1220).
when you reach egypt, replenish your armies, they should be pretty worn down, and remember not to press your regions while you take north africa, having a region rebel is not a good thing at this point since it brings your rep down and etc.
when replenished, take egypt and then start taking apart the holy lands. youll get offers from the hosplitars and other groups, you can try and vassalize them, and i think there is a good chance since the only time ive vassalized was with the grandmaster of the hosplitars. remember to give all your lands to your family as much as possible while doing all of this, having lands in the middle east exposes you too much. meanwhile, the enemy will be forced to go ALL the way back to iberia to fight you since they obviously can't find your army. when enemies approach your lands in iberia, use your vassal's armies for brief moments in deterring the enemy.
doing that little strategy will easily get you all the middle east, ukraine and crimea by 1250. i gained the french crown and united many of the italian lands by war. my capitol was located in ventia (-_-), so my personal army was about 15000 strong total