I find Iberia to be extremely satisfying. I takes patience, a lot of money, maybe a few allies. But a gradual creep into neighbouring (and high-tech!) provinces, seeing the positive effects on the rest of my provinces, and the slow change of colour in both state and religion, is oh-so-much-more satisfying than crusades for Jerusalem, which is a true bottomless pit for casualties.
In my current game (I'm playing England), I somehow managed to marry my son to the soon-to-be-queen of Castille. Kinslayer on a massive scale she may be (four siblings assassinated/executed I believe) but Dalia "the Lion" is proving adept at nibbling away at the Moors! Without my help, each war ends in stalemate; with my help, victory.
Also, remember that the reconquista took a loooong time, and it certainly wasn't a historical inevitability.
PS... And it doesn't get easier. When I got down to Seville and Cordoba, I couldn't believe the castle garrison size! (2K+)