You'd think I wouldn't have to come across assigned-seating in college, and I haven't for almost 4 years, but this semester I have one class that mandates it... It's so dumb, as I sat in the front on the first day, but I don't want to stay in the front. What if the professor sees me yawning. 6 times. D'8
Big lecture halls that can contain 100+ students: I sit wherever there's a spot that suits my mood. If I want to pay attention, I sit in the front. If I wanna be a slacker and either work on another assignment or goof off on my tablet, I sit in the back.
Smaller classrooms: I sit in the middle and usually off-center. I like being able to sit against walls and look at the entire classroom. With our backs to the wall, the darkness would fall.