Hmmm. That's a good question. I'm assuming you're just talking about NPC's for a quick encounter? Well, most students and faculty remain in a humanoid form most of the time (which admittedly is kind of leftover from earlier versions of the RP when there were more human students and the supernatural thing was supposed to be sort of secretive, but since that's no longer the case it's a bit less necessary, but, eh *shrugs*), but um, I suppose if you want some ideas, you can just look over the CS's and see what our player characters and even NPC's (most if not all of which are former player characters) are like. I'm sure the school has more of that.
Also, what exactly is your intention with these random encounters? Not something that would be the focus of too many posts, right? I just want to make sure there's more PC-PC interaction than PC-NPC, here.