I carry a laptop around on a daily basis as well. I see the following alternatives:
A traditional laptop bag, which you use now. Agree that it's stylish but quite uncomfortable for extended walking.
A laptop backup. Not my style personally, but I'm sure it would help significantly with the back or shoulder pain. You should be able to find some fun ones online in color etc.
A regular tote that fits your laptop. I do that for my regular work days; I bought a large tote at H&M and put my laptop in there. It's much lighter than a regular laptop bag. Of course, it also doesn't protect the laptop very well (I don't even have a laptop sleeve yet, though i plan to buy one). And it's still pretty harsh on your back and shoulders.
A laptop bag with wheels. I just ordered one of those for traveling, especially walking around in airports, since the laptop bag doubles as my carry-on bag. Once you add a bottle of water, a book, a couple magazines, then it gets really heavy and I was sick of carrying a shoulder bag. Not sure this would work for you on campus, though. It's probably quite a "business woman look" more than a student look. Also, of course the addition of the wheels makes the bag extremely heavy when you do pick it up. There are bags with removable wheels/handles. I ordered the sleek red one with the clasp I linked to on the related thread Marianne copied below.
So in summary, my own solution is a regular big tote for everyday, and a wheeled laptop bag for biz trips. Hope that helps a little bit.
