Monsters with Reason

From lingering around other people's games, it has become apparent to me that a lot of times monstrous demihumans are simply aggressors. When they are encountered, they may demand some gold, but more times than not they will attack just for fun. I think that there's something to be said for a good fight now and then, but there's also something to be said about giving your monstrous demihumans (and enemyhumans and regular demihumans) the power of reasoned thought. Most small parties of goblins, for example, should know better than to attack well-armed and well-armored adventurers unless they have a huge advantage in numbers.

Smart foes are the basis of a challenging game, and they also help to bring a sense of realism to the setting. Not every monstrous demihuman is a ravening beast that desires nothing but to bathe in the blood of their foes. Many are quite capable (and should be portrayed as such) of advanced tactical maneuvers, but also in judging the relative strength of their enemies and making a decision based on whether or not they think violence is the best solution. Hell, violence is almost never the best solution. Unless they are particularly bloodthirsty (gnolls might qualify here, and hungry orcs probably can as well) there's no reason to go out of their way to attack someone that they can intimidate instead.