Sadly, rakshasas are one of D&D's underused and underappreciated monsters. Some notes gleaned from other products.
The 3.0 Manual of the Planes places colonies of rakshasas on Acheron, the lawful neutral (with evil tendencies) plane of metal and war.
The AD&D Monstrous Manual says that rakshasas are incredibly devious and tricky, but have a strict, if perverse, code of honor. They live opulently, dressed in finery and behaving like noblemen. Females, or rakshasi, are treated like property. The knights of their society are called rukhs (which is a good title for an advanced rakshasa) and they are ruled by rajas and maharajas.
Of course, the rakshasas are actual mythological creatures, taken from Hindi legends. There, they were the enemies of the gods and trickster figures who posed as trusted relatives in order to kill and steal from the unlucky and not-clever-enough. Not all mythological rakshasas have tiger heads- some have the heads of boars, bears or other beasts. Their king is Ravana, who, in addition to being almost as powerful as a god, has ten heads and eight arms.
Demiurge out.