Would it be a bad idea to have more diplomatic options between christian rulers and muslim rulers and even possibly form temporary alliances. Historically, it wasn't totally unrealistic as people make it out to be. In the holy land alone, there were many cases where christian rulers allied with muslim rulers against other muslims and vice versa. Yes I know there were the crusades and all, but even the crusades were politically motivated. Gameplay wise, it would make it even more sense to have possible alliances. You see a massive green blob forming in Iberia, it would be in the best interest for remaining muslim emirates to band togethor with remaining christian kings against a massive blob that would devour them all. I think it would allow for more interesting and balanced gameplay.
Also, have the option to pay tribute. Instead of having an alliances you could pay off nearby neighbors from declaring war on you.
Also, have the option to pay tribute. Instead of having an alliances you could pay off nearby neighbors from declaring war on you.