JanSport Superbreak: the classic backpack
This backpack is awesome... you can't go wrong! They're really durable and provide a pocket to separate your smaller things from your larger stuff. I think the best thing about it, though, is that it provides you room for the necessities and isn't too big so you don't over-pack and break your back!
i used to dislike backpacks because they make me look smaller... not until i had this bag (i got a pink cherry daiquiri one, spring 2009 model)! this changed my perception about backpacks (i thought they were boring and too boyish for me). it made me enjoy going to school more. aside from those, it's very durable, doesn't feel like you're carrying too much things. and a lot of things can actually fit inside. i know this would last for years. :)