Ben,

If you have to go back to a bag for the laptop look at Oakley brand bags. I have two, the one listed above for the MacBook and a true backpack for my 5 ton pc laptop (17" HP). They do something different with the suspension that makes the load much more bearable, even with bad shoulders. Swiss Army also has a good one. I actually picked both up at the Apple store, one in your neck of the woods. YMMV