I'm in a Bachelor of Commerce program right now, so I can field that question.
If you're looking at a co-op program, then it tends to be a bit more competative to enter than the regular program.
Advantage: You get set up with a job, and don't have to work the system yourself in that regard.
Disadvantage: It's a bit more rigorous, given the fact that you need to be going full time during two terms to compensate for the time you spend at the job (for the third term).
If you're introverted, then you might have trouble getting "out there" on your own. In this regard, a placement could help. This is especially to your advantage if you have no trouble with being civil to people, but just aren't very chatty. Once you have job experience in the field, it makes finding further employment much easier.
As for classes, it's true that extroverted people tend to fare better. Especially if the school you're looking at has class participation marks. If that's so, you might want to gravitate towards areas that introverted people enjoy, such as Accounting, Supply Chain, or Actuarial Mathematics. Or, if you want to combine Management and Computers, you can try for a Management Info Systems major (if the school offers it).
In addition, if the school has a good Career Development Centre, you might want to keep in contact with them for resume and interview tips, as well as how to behave at Banquets and Wine and Cheeses. I found it to be really helpful, and even NTs struggle with that sometimes.
