I used to use a tucano second skin, but then found the be.ez cases with that incredible memory foam. A truly excellent case. Once its in thsi case, I then put it in another bag by be.ze. Its pretty decent, although can be a bit tough on the shoulder after 20 minutes or so
I think this would be the perfect backpack for you. It has a padded section wich looks like it is made exactly for the 13" MBP. It just fits perfectly into it. I had this bag for almost 2 years by now even before i got the MBP and it is great. very spacious if you are a college student as it can carry a lot of books as well. I got it for like 40 $ at sportscheck. very durable as well. Still looks as good as new.